diff --git a/aggregate.go b/aggregate.go
index 92cb0eb7..5c65f594 100644
--- a/aggregate.go
+++ b/aggregate.go
@@ -88,7 +88,7 @@ type AggregateStoreError struct {
 }
 
 // Error implements the Error method of the error interface.
-func (e AggregateStoreError) Error() string {
+func (e *AggregateStoreError) Error() string {
 	str := "aggregate store: "
 
 	if e.Op != "" {
@@ -113,12 +113,12 @@ func (e AggregateStoreError) Error() string {
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e AggregateStoreError) Unwrap() error {
+func (e *AggregateStoreError) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e AggregateStoreError) Cause() error {
+func (e *AggregateStoreError) Cause() error {
 	return e.Unwrap()
 }
 
@@ -129,17 +129,17 @@ type AggregateError struct {
 }
 
 // Error implements the Error method of the errors.Error interface.
-func (e AggregateError) Error() string {
+func (e *AggregateError) Error() string {
 	return "aggregate error: " + e.Err.Error()
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e AggregateError) Unwrap() error {
+func (e *AggregateError) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e AggregateError) Cause() error {
+func (e *AggregateError) Cause() error {
 	return e.Unwrap()
 }
 
diff --git a/aggregatestore/events/aggregatestore.go b/aggregatestore/events/aggregatestore.go
index b3df8e18..ad10732c 100644
--- a/aggregatestore/events/aggregatestore.go
+++ b/aggregatestore/events/aggregatestore.go
@@ -61,7 +61,7 @@ func NewAggregateStore(store eh.EventStore) (*AggregateStore, error) {
 func (r *AggregateStore) Load(ctx context.Context, aggregateType eh.AggregateType, id uuid.UUID) (eh.Aggregate, error) {
 	agg, err := eh.CreateAggregate(aggregateType, id)
 	if err != nil {
-		return nil, eh.AggregateStoreError{
+		return nil, &eh.AggregateStoreError{
 			Err:           err,
 			Op:            eh.AggregateStoreOpLoad,
 			AggregateType: aggregateType,
@@ -71,7 +71,7 @@ func (r *AggregateStore) Load(ctx context.Context, aggregateType eh.AggregateTyp
 
 	a, ok := agg.(VersionedAggregate)
 	if !ok {
-		return nil, eh.AggregateStoreError{
+		return nil, &eh.AggregateStoreError{
 			Err:           ErrAggregateNotVersioned,
 			Op:            eh.AggregateStoreOpLoad,
 			AggregateType: aggregateType,
@@ -81,7 +81,7 @@ func (r *AggregateStore) Load(ctx context.Context, aggregateType eh.AggregateTyp
 
 	events, err := r.store.Load(ctx, a.EntityID())
 	if err != nil && !errors.Is(err, eh.ErrAggregateNotFound) {
-		return nil, eh.AggregateStoreError{
+		return nil, &eh.AggregateStoreError{
 			Err:           err,
 			Op:            eh.AggregateStoreOpLoad,
 			AggregateType: aggregateType,
@@ -90,7 +90,7 @@ func (r *AggregateStore) Load(ctx context.Context, aggregateType eh.AggregateTyp
 	}
 
 	if err := r.applyEvents(ctx, a, events); err != nil {
-		return nil, eh.AggregateStoreError{
+		return nil, &eh.AggregateStoreError{
 			Err:           err,
 			Op:            eh.AggregateStoreOpLoad,
 			AggregateType: aggregateType,
@@ -106,7 +106,7 @@ func (r *AggregateStore) Load(ctx context.Context, aggregateType eh.AggregateTyp
 func (r *AggregateStore) Save(ctx context.Context, agg eh.Aggregate) error {
 	a, ok := agg.(VersionedAggregate)
 	if !ok {
-		return eh.AggregateStoreError{
+		return &eh.AggregateStoreError{
 			Err:           ErrAggregateNotVersioned,
 			Op:            eh.AggregateStoreOpSave,
 			AggregateType: agg.AggregateType(),
@@ -121,7 +121,7 @@ func (r *AggregateStore) Save(ctx context.Context, agg eh.Aggregate) error {
 	}
 
 	if err := r.store.Save(ctx, events, a.AggregateVersion()); err != nil {
-		return eh.AggregateStoreError{
+		return &eh.AggregateStoreError{
 			Err:           err,
 			Op:            eh.AggregateStoreOpSave,
 			AggregateType: agg.AggregateType(),
@@ -134,7 +134,7 @@ func (r *AggregateStore) Save(ctx context.Context, agg eh.Aggregate) error {
 	// Apply the events in case the aggregate needs to be further used
 	// after this save. Currently it is not reused.
 	if err := r.applyEvents(ctx, a, events); err != nil {
-		return eh.AggregateStoreError{
+		return &eh.AggregateStoreError{
 			Err:           err,
 			Op:            eh.AggregateStoreOpSave,
 			AggregateType: agg.AggregateType(),
diff --git a/aggregatestore/events/aggregatestore_test.go b/aggregatestore/events/aggregatestore_test.go
index e96a1da8..4cd16f43 100644
--- a/aggregatestore/events/aggregatestore_test.go
+++ b/aggregatestore/events/aggregatestore_test.go
@@ -203,7 +203,7 @@ func TestAggregateStore_SaveEvents(t *testing.T) {
 	storeErr := errors.New("store error")
 	eventStore.Err = storeErr
 	err = store.Save(ctx, agg)
-	aggStoreErr := eh.AggregateStoreError{}
+	aggStoreErr := &eh.AggregateStoreError{}
 	if !errors.As(err, &aggStoreErr) || !errors.Is(err, storeErr) {
 		t.Error("there should be an aggregate store error:", err)
 	}
@@ -214,7 +214,7 @@ func TestAggregateStore_SaveEvents(t *testing.T) {
 	aggErr := errors.New("aggregate error")
 	agg.err = aggErr
 	err = store.Save(ctx, agg)
-	aggStoreErr = eh.AggregateStoreError{}
+	aggStoreErr = &eh.AggregateStoreError{}
 	if !errors.As(err, &aggStoreErr) || !errors.Is(err, aggErr) {
 		t.Error("there should be an aggregate store error:", err)
 	}
diff --git a/aggregatestore/model/aggregatestore_test.go b/aggregatestore/model/aggregatestore_test.go
index b2eeb554..af288b7c 100644
--- a/aggregatestore/model/aggregatestore_test.go
+++ b/aggregatestore/model/aggregatestore_test.go
@@ -55,7 +55,7 @@ func TestAggregateStore_LoadNotFound(t *testing.T) {
 	ctx := context.Background()
 
 	id := uuid.New()
-	repo.LoadErr = eh.RepoError{Err: eh.ErrEntityNotFound}
+	repo.LoadErr = &eh.RepoError{Err: eh.ErrEntityNotFound}
 	agg, err := store.Load(ctx, AggregateType, id)
 	if err != nil {
 		t.Fatal("there should be no error:", err)
diff --git a/command_check.go b/command_check.go
index 6052fc72..4e580e01 100644
--- a/command_check.go
+++ b/command_check.go
@@ -33,7 +33,7 @@ type CommandFieldError struct {
 }
 
 // Error implements the Error method of the error interface.
-func (c CommandFieldError) Error() string {
+func (c *CommandFieldError) Error() string {
 	return "missing field: " + c.Field
 }
 
@@ -62,7 +62,7 @@ func CheckCommand(cmd Command) error {
 		}
 
 		if zero {
-			return CommandFieldError{field.Name}
+			return &CommandFieldError{field.Name}
 		}
 	}
 	return nil
diff --git a/commandhandler/aggregate/commandhandler.go b/commandhandler/aggregate/commandhandler.go
index 2fa32ab9..d5006cb6 100644
--- a/commandhandler/aggregate/commandhandler.go
+++ b/commandhandler/aggregate/commandhandler.go
@@ -67,7 +67,7 @@ func (h *CommandHandler) HandleCommand(ctx context.Context, cmd eh.Command) erro
 	}
 
 	if err = a.HandleCommand(ctx, cmd); err != nil {
-		return eh.AggregateError{Err: err}
+		return &eh.AggregateError{Err: err}
 	}
 
 	return h.store.Save(ctx, a)
diff --git a/commandhandler/aggregate/commandhandler_test.go b/commandhandler/aggregate/commandhandler_test.go
index dccf9197..bd7d2611 100644
--- a/commandhandler/aggregate/commandhandler_test.go
+++ b/commandhandler/aggregate/commandhandler_test.go
@@ -99,7 +99,7 @@ func TestCommandHandler_ErrorInHandler(t *testing.T) {
 		Content: "command1",
 	}
 	err := h.HandleCommand(context.Background(), cmd)
-	var aggregateErr eh.AggregateError
+	aggregateErr := &eh.AggregateError{}
 	if !errors.As(err, &aggregateErr) || !errors.Is(err, commandErr) {
 		t.Error("there should be a command error:", err)
 	}
diff --git a/eventbus.go b/eventbus.go
index 71ba0a8e..2f0e9e86 100644
--- a/eventbus.go
+++ b/eventbus.go
@@ -31,7 +31,7 @@ type EventBus interface {
 	AddHandler(context.Context, EventMatcher, EventHandler) error
 
 	// Errors returns an error channel where async handling errors are sent.
-	Errors() <-chan EventBusError
+	Errors() <-chan *EventBusError
 
 	// Close closes the EventBus and waits for all handlers to finish.
 	Close() error
@@ -58,7 +58,7 @@ type EventBusError struct {
 }
 
 // Error implements the Error method of the error interface.
-func (e EventBusError) Error() string {
+func (e *EventBusError) Error() string {
 	str := "event bus: "
 
 	if e.Err != nil {
@@ -75,11 +75,11 @@ func (e EventBusError) Error() string {
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e EventBusError) Unwrap() error {
+func (e *EventBusError) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e EventBusError) Cause() error {
+func (e *EventBusError) Cause() error {
 	return e.Unwrap()
 }
diff --git a/eventbus/gcp/eventbus.go b/eventbus/gcp/eventbus.go
index 1c1949b4..c1e6d681 100644
--- a/eventbus/gcp/eventbus.go
+++ b/eventbus/gcp/eventbus.go
@@ -38,7 +38,7 @@ type EventBus struct {
 	topic        *pubsub.Topic
 	registered   map[eh.EventHandlerType]struct{}
 	registeredMu sync.RWMutex
-	errCh        chan eh.EventBusError
+	errCh        chan *eh.EventBusError
 	cctx         context.Context
 	cancel       context.CancelFunc
 	wg           sync.WaitGroup
@@ -52,7 +52,7 @@ func NewEventBus(projectID, appID string, options ...Option) (*EventBus, error)
 	b := &EventBus{
 		appID:      appID,
 		registered: map[eh.EventHandlerType]struct{}{},
-		errCh:      make(chan eh.EventBusError, 100),
+		errCh:      make(chan *eh.EventBusError, 100),
 		cctx:       ctx,
 		cancel:     cancel,
 		codec:      &json.EventCodec{},
@@ -206,7 +206,7 @@ func (b *EventBus) AddHandler(ctx context.Context, m eh.EventMatcher, h eh.Event
 }
 
 // Errors implements the Errors method of the eventhorizon.EventBus interface.
-func (b *EventBus) Errors() <-chan eh.EventBusError {
+func (b *EventBus) Errors() <-chan *eh.EventBusError {
 	return b.errCh
 }
 
@@ -231,7 +231,7 @@ func (b *EventBus) handle(m eh.EventMatcher, h eh.EventHandler, sub *pubsub.Subs
 		if err := sub.Receive(b.cctx, b.handler(m, h)); err != nil {
 			err = fmt.Errorf("could not receive: %w", err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err}:
+			case b.errCh <- &eh.EventBusError{Err: err}:
 			default:
 				log.Printf("eventhorizon: missed error in GCP event bus: %s", err)
 			}
@@ -250,7 +250,7 @@ func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler) func(ctx contex
 		if err != nil {
 			err = fmt.Errorf("could not unmarshal event: %w", err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx}:
+			case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx}:
 			default:
 				log.Printf("eventhorizon: missed error in GCP event bus: %s", err)
 			}
@@ -268,7 +268,7 @@ func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler) func(ctx contex
 		if err := h.HandleEvent(ctx, event); err != nil {
 			err = fmt.Errorf("could not handle event (%s): %w", h.HandlerType(), err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx, Event: event}:
+			case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx, Event: event}:
 			default:
 				log.Printf("eventhorizon: missed error in GCP event bus: %s", err)
 			}
diff --git a/eventbus/kafka/eventbus.go b/eventbus/kafka/eventbus.go
index 84c13d94..c0da3592 100644
--- a/eventbus/kafka/eventbus.go
+++ b/eventbus/kafka/eventbus.go
@@ -39,7 +39,7 @@ type EventBus struct {
 	writer       *kafka.Writer
 	registered   map[eh.EventHandlerType]struct{}
 	registeredMu sync.RWMutex
-	errCh        chan eh.EventBusError
+	errCh        chan *eh.EventBusError
 	cctx         context.Context
 	cancel       context.CancelFunc
 	wg           sync.WaitGroup
@@ -55,7 +55,7 @@ func NewEventBus(addr, appID string, options ...Option) (*EventBus, error) {
 		appID:      appID,
 		topic:      appID + "_events",
 		registered: map[eh.EventHandlerType]struct{}{},
-		errCh:      make(chan eh.EventBusError, 100),
+		errCh:      make(chan *eh.EventBusError, 100),
 		cctx:       ctx,
 		cancel:     cancel,
 		codec:      &json.EventCodec{},
@@ -217,7 +217,7 @@ func (b *EventBus) AddHandler(ctx context.Context, m eh.EventMatcher, h eh.Event
 }
 
 // Errors implements the Errors method of the eventhorizon.EventBus interface.
-func (b *EventBus) Errors() <-chan eh.EventBusError {
+func (b *EventBus) Errors() <-chan *eh.EventBusError {
 	return b.errCh
 }
 
@@ -249,7 +249,7 @@ func (b *EventBus) handle(m eh.EventMatcher, h eh.EventHandler, r *kafka.Reader)
 		} else if err != nil {
 			err = fmt.Errorf("could not fetch message: %w", err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err}:
+			case b.errCh <- &eh.EventBusError{Err: err}:
 			default:
 				log.Printf("eventhorizon: missed error in Kafka event bus: %s", err)
 			}
@@ -258,8 +258,7 @@ func (b *EventBus) handle(m eh.EventMatcher, h eh.EventHandler, r *kafka.Reader)
 			continue
 		}
 
-		var noBusError eh.EventBusError
-		if err := handler(b.cctx, msg); err != noBusError {
+		if err := handler(b.cctx, msg); err != nil {
 			select {
 			case b.errCh <- err:
 			default:
@@ -272,7 +271,7 @@ func (b *EventBus) handle(m eh.EventMatcher, h eh.EventHandler, r *kafka.Reader)
 		if err := r.CommitMessages(context.Background(), msg); err != nil {
 			err = fmt.Errorf("could not commit message: %w", err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err}:
+			case b.errCh <- &eh.EventBusError{Err: err}:
 			default:
 				log.Printf("eventhorizon: missed error in Kafka event bus: %s", err)
 			}
@@ -284,11 +283,11 @@ func (b *EventBus) handle(m eh.EventMatcher, h eh.EventHandler, r *kafka.Reader)
 	}
 }
 
-func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler, r *kafka.Reader) func(ctx context.Context, msg kafka.Message) eh.EventBusError {
-	return func(ctx context.Context, msg kafka.Message) eh.EventBusError {
+func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler, r *kafka.Reader) func(ctx context.Context, msg kafka.Message) *eh.EventBusError {
+	return func(ctx context.Context, msg kafka.Message) *eh.EventBusError {
 		event, ctx, err := b.codec.UnmarshalEvent(ctx, msg.Value)
 		if err != nil {
-			return eh.EventBusError{
+			return &eh.EventBusError{
 				Err: fmt.Errorf("could not unmarshal event: %w", err),
 				Ctx: ctx,
 			}
@@ -296,18 +295,18 @@ func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler, r *kafka.Reader
 
 		// Ignore non-matching events.
 		if !m.Match(event) {
-			return eh.EventBusError{}
+			return nil
 		}
 
 		// Handle the event if it did match.
 		if err := h.HandleEvent(ctx, event); err != nil {
-			return eh.EventBusError{
+			return &eh.EventBusError{
 				Err:   fmt.Errorf("could not handle event (%s): %w", h.HandlerType(), err),
 				Ctx:   ctx,
 				Event: event,
 			}
 		}
 
-		return eh.EventBusError{}
+		return nil
 	}
 }
diff --git a/eventbus/local/eventbus.go b/eventbus/local/eventbus.go
index 3f3c2c4f..623a56ed 100644
--- a/eventbus/local/eventbus.go
+++ b/eventbus/local/eventbus.go
@@ -34,7 +34,7 @@ type EventBus struct {
 	group        *Group
 	registered   map[eh.EventHandlerType]struct{}
 	registeredMu sync.RWMutex
-	errCh        chan eh.EventBusError
+	errCh        chan *eh.EventBusError
 	cctx         context.Context
 	cancel       context.CancelFunc
 	wg           sync.WaitGroup
@@ -48,7 +48,7 @@ func NewEventBus(options ...Option) *EventBus {
 	b := &EventBus{
 		group:      NewGroup(),
 		registered: map[eh.EventHandlerType]struct{}{},
-		errCh:      make(chan eh.EventBusError, 100),
+		errCh:      make(chan *eh.EventBusError, 100),
 		cctx:       ctx,
 		cancel:     cancel,
 		codec:      &json.EventCodec{},
@@ -127,7 +127,7 @@ func (b *EventBus) AddHandler(ctx context.Context, m eh.EventMatcher, h eh.Event
 }
 
 // Errors implements the Errors method of the eventhorizon.EventBus interface.
-func (b *EventBus) Errors() <-chan eh.EventBusError {
+func (b *EventBus) Errors() <-chan *eh.EventBusError {
 	return b.errCh
 }
 
@@ -160,7 +160,7 @@ func (b *EventBus) handle(m eh.EventMatcher, h eh.EventHandler, ch <-chan []byte
 			if err != nil {
 				err = fmt.Errorf("could not unmarshal event: %w", err)
 				select {
-				case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx}:
+				case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx}:
 				default:
 					log.Printf("eventhorizon: missed error in local event bus: %s", err)
 				}
@@ -176,7 +176,7 @@ func (b *EventBus) handle(m eh.EventMatcher, h eh.EventHandler, ch <-chan []byte
 			if err := h.HandleEvent(ctx, event); err != nil {
 				err = fmt.Errorf("could not handle event (%s): %s", h.HandlerType(), err.Error())
 				select {
-				case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx, Event: event}:
+				case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx, Event: event}:
 				default:
 					log.Printf("eventhorizon: missed error in local event bus: %s", err)
 				}
diff --git a/eventbus/nats/eventbus.go b/eventbus/nats/eventbus.go
index 8a547018..1ff631a1 100644
--- a/eventbus/nats/eventbus.go
+++ b/eventbus/nats/eventbus.go
@@ -38,7 +38,7 @@ type EventBus struct {
 	connOpts     []nats.Option
 	registered   map[eh.EventHandlerType]struct{}
 	registeredMu sync.RWMutex
-	errCh        chan eh.EventBusError
+	errCh        chan *eh.EventBusError
 	cctx         context.Context
 	cancel       context.CancelFunc
 	wg           sync.WaitGroup
@@ -53,7 +53,7 @@ func NewEventBus(url, appID string, options ...Option) (*EventBus, error) {
 		appID:      appID,
 		streamName: appID + "_events",
 		registered: map[eh.EventHandlerType]struct{}{},
-		errCh:      make(chan eh.EventBusError, 100),
+		errCh:      make(chan *eh.EventBusError, 100),
 		cctx:       ctx,
 		cancel:     cancel,
 		codec:      &json.EventCodec{},
@@ -179,7 +179,7 @@ func (b *EventBus) AddHandler(ctx context.Context, m eh.EventMatcher, h eh.Event
 }
 
 // Errors implements the Errors method of the eventhorizon.EventBus interface.
-func (b *EventBus) Errors() <-chan eh.EventBusError {
+func (b *EventBus) Errors() <-chan *eh.EventBusError {
 	return b.errCh
 }
 
@@ -215,7 +215,7 @@ func (b *EventBus) handler(ctx context.Context, m eh.EventMatcher, h eh.EventHan
 		if err != nil {
 			err = fmt.Errorf("could not unmarshal event: %w", err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx}:
+			case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx}:
 			default:
 				log.Printf("eventhorizon: missed error in NATS event bus: %s", err)
 			}
@@ -233,7 +233,7 @@ func (b *EventBus) handler(ctx context.Context, m eh.EventMatcher, h eh.EventHan
 		if err := h.HandleEvent(ctx, event); err != nil {
 			err = fmt.Errorf("could not handle event (%s): %w", h.HandlerType(), err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx, Event: event}:
+			case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx, Event: event}:
 			default:
 				log.Printf("eventhorizon: missed error in NATS event bus: %s", err)
 			}
diff --git a/eventbus/redis/eventbus.go b/eventbus/redis/eventbus.go
index e6b08237..155c8a6c 100644
--- a/eventbus/redis/eventbus.go
+++ b/eventbus/redis/eventbus.go
@@ -39,7 +39,7 @@ type EventBus struct {
 	clientOpts   *redis.Options
 	registered   map[eh.EventHandlerType]struct{}
 	registeredMu sync.RWMutex
-	errCh        chan eh.EventBusError
+	errCh        chan *eh.EventBusError
 	cctx         context.Context
 	cancel       context.CancelFunc
 	wg           sync.WaitGroup
@@ -55,7 +55,7 @@ func NewEventBus(addr, appID, clientID string, options ...Option) (*EventBus, er
 		clientID:   clientID,
 		streamName: appID + "_events",
 		registered: map[eh.EventHandlerType]struct{}{},
-		errCh:      make(chan eh.EventBusError, 100),
+		errCh:      make(chan *eh.EventBusError, 100),
 		cctx:       ctx,
 		cancel:     cancel,
 		codec:      &json.EventCodec{},
@@ -178,7 +178,7 @@ func (b *EventBus) AddHandler(ctx context.Context, m eh.EventMatcher, h eh.Event
 }
 
 // Errors implements the Errors method of the eventhorizon.EventBus interface.
-func (b *EventBus) Errors() <-chan eh.EventBusError {
+func (b *EventBus) Errors() <-chan *eh.EventBusError {
 	return b.errCh
 }
 
@@ -208,7 +208,7 @@ func (b *EventBus) handle(m eh.EventMatcher, h eh.EventHandler, groupName string
 		} else if err != nil {
 			err = fmt.Errorf("could not receive: %w", err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err}:
+			case b.errCh <- &eh.EventBusError{Err: err}:
 			default:
 				log.Printf("eventhorizon: missed error in Redis event bus: %s", err)
 			}
@@ -236,7 +236,7 @@ func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler, groupName strin
 		if err != nil {
 			err = fmt.Errorf("could not unmarshal event: %w", err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx}:
+			case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx}:
 			default:
 				log.Printf("eventhorizon: missed error in Redis event bus: %s", err)
 			}
@@ -250,7 +250,7 @@ func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler, groupName strin
 			if err != nil {
 				err = fmt.Errorf("could not ack event: %w", err)
 				select {
-				case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx}:
+				case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx}:
 				default:
 					log.Printf("eventhorizon: missed error in Redis event bus: %s", err)
 				}
@@ -262,7 +262,7 @@ func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler, groupName strin
 		if err := h.HandleEvent(ctx, event); err != nil {
 			err = fmt.Errorf("could not handle event (%s): %w", h.HandlerType(), err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx, Event: event}:
+			case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx, Event: event}:
 			default:
 				log.Printf("eventhorizon: missed error in Redis event bus: %s", err)
 			}
@@ -274,7 +274,7 @@ func (b *EventBus) handler(m eh.EventMatcher, h eh.EventHandler, groupName strin
 		if err != nil {
 			err = fmt.Errorf("could not ack event: %w", err)
 			select {
-			case b.errCh <- eh.EventBusError{Err: err, Ctx: ctx}:
+			case b.errCh <- &eh.EventBusError{Err: err, Ctx: ctx}:
 			default:
 				log.Printf("eventhorizon: missed error in Redis event bus: %s", err)
 			}
diff --git a/eventbus_test.go b/eventbus_test.go
index 48cabc87..2c3d5c3d 100644
--- a/eventbus_test.go
+++ b/eventbus_test.go
@@ -56,7 +56,7 @@ func TestEventBusError(t *testing.T) {
 
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
-			busError := EventBusError{
+			busError := &EventBusError{
 				Err:   tc.err,
 				Event: tc.event,
 			}
diff --git a/eventhandler.go b/eventhandler.go
index c080066d..bf638d43 100644
--- a/eventhandler.go
+++ b/eventhandler.go
@@ -68,7 +68,7 @@ type EventHandlerError struct {
 }
 
 // Error implements the Error method of the errors.Error interface.
-func (e EventHandlerError) Error() string {
+func (e *EventHandlerError) Error() string {
 	str := "could not handle event: "
 
 	if e.Err != nil {
@@ -85,11 +85,11 @@ func (e EventHandlerError) Error() string {
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e EventHandlerError) Unwrap() error {
+func (e *EventHandlerError) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e EventHandlerError) Cause() error {
+func (e *EventHandlerError) Cause() error {
 	return e.Unwrap()
 }
diff --git a/eventhandler/projector/eventhandler.go b/eventhandler/projector/eventhandler.go
index 3724cbfb..730c7f3a 100644
--- a/eventhandler/projector/eventhandler.go
+++ b/eventhandler/projector/eventhandler.go
@@ -65,7 +65,7 @@ type Error struct {
 }
 
 // Error implements the Error method of the errors.Error interface.
-func (e Error) Error() string {
+func (e *Error) Error() string {
 	str := "projector '" + e.Projector + "': "
 
 	if e.Err != nil {
@@ -86,12 +86,12 @@ func (e Error) Error() string {
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e Error) Unwrap() error {
+func (e *Error) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e Error) Cause() error {
+func (e *Error) Cause() error {
 	return e.Unwrap()
 }
 
@@ -195,7 +195,7 @@ retryOnce:
 	entity, err := h.repo.Find(findCtx, id)
 	if errors.Is(err, eh.ErrEntityNotFound) {
 		if h.factoryFn == nil {
-			return Error{
+			return &Error{
 				Err:       ErrModelNotSet,
 				Projector: h.projector.ProjectorType().String(),
 				Event:     event,
@@ -210,14 +210,14 @@ retryOnce:
 			goto retryOnce
 		}
 
-		return Error{
+		return &Error{
 			Err:       fmt.Errorf("could not load entity with correct version: %w", err),
 			Projector: h.projector.ProjectorType().String(),
 			Event:     event,
 			EntityID:  id,
 		}
 	} else if err != nil {
-		return Error{
+		return &Error{
 			Err:       fmt.Errorf("could not load entity: %w", err),
 			Projector: h.projector.ProjectorType().String(),
 			Event:     event,
@@ -243,7 +243,7 @@ retryOnce:
 				goto retryOnce
 			}
 
-			return Error{
+			return &Error{
 				Err:           eh.ErrIncorrectEntityVersion,
 				Projector:     h.projector.ProjectorType().String(),
 				Event:         event,
@@ -256,7 +256,7 @@ retryOnce:
 	// Run the projection, which will possibly increment the version.
 	newEntity, err := h.projector.Project(ctx, event, entity)
 	if err != nil {
-		return Error{
+		return &Error{
 			Err:           fmt.Errorf("could not project: %w", err),
 			Projector:     h.projector.ProjectorType().String(),
 			Event:         event,
@@ -269,7 +269,7 @@ retryOnce:
 	if newEntity, ok := newEntity.(eh.Versionable); ok {
 		entityVersion = newEntity.AggregateVersion()
 		if newEntity.AggregateVersion() != event.Version() {
-			return Error{
+			return &Error{
 				Err:           ErrIncorrectProjectedEntityVersion,
 				Projector:     h.projector.ProjectorType().String(),
 				Event:         event,
@@ -282,7 +282,7 @@ retryOnce:
 	// Update or remove the model.
 	if newEntity != nil {
 		if newEntity.EntityID() != id {
-			return Error{
+			return &Error{
 				Err:           fmt.Errorf("incorrect entity ID after projection"),
 				Projector:     h.projector.ProjectorType().String(),
 				Event:         event,
@@ -291,7 +291,7 @@ retryOnce:
 			}
 		}
 		if err := h.repo.Save(ctx, newEntity); err != nil {
-			return Error{
+			return &Error{
 				Err:           fmt.Errorf("could not save: %w", err),
 				Projector:     h.projector.ProjectorType().String(),
 				Event:         event,
@@ -301,7 +301,7 @@ retryOnce:
 		}
 	} else {
 		if err := h.repo.Remove(ctx, id); err != nil {
-			return Error{
+			return &Error{
 				Err:           fmt.Errorf("could not remove: %w", err),
 				Projector:     h.projector.ProjectorType().String(),
 				Event:         event,
diff --git a/eventhandler/projector/eventhandler_test.go b/eventhandler/projector/eventhandler_test.go
index aa9366a3..a4eba76a 100644
--- a/eventhandler/projector/eventhandler_test.go
+++ b/eventhandler/projector/eventhandler_test.go
@@ -46,7 +46,7 @@ func TestEventHandler_CreateModel(t *testing.T) {
 	entity := &mocks.SimpleModel{
 		ID: id,
 	}
-	repo.LoadErr = eh.RepoError{
+	repo.LoadErr = &eh.RepoError{
 		Err: eh.ErrEntityNotFound,
 	}
 	projector.newEntity = entity
@@ -151,15 +151,10 @@ func TestEventHandler_UpdateModelWithVersion(t *testing.T) {
 	// Handling a future event with a gap in versions should produce an error.
 	futureEvent := eh.NewEvent(mocks.EventType, eventData, timestamp,
 		eh.ForAggregate(mocks.AggregateType, id, 8))
-	expectedErr := Error{
-		Err:           eh.ErrIncorrectEntityVersion,
-		Projector:     TestProjectorType.String(),
-		Event:         futureEvent,
-		EntityID:      id,
-		EntityVersion: 1,
-	}
+	errType := &Error{}
 	err := handler.HandleEvent(ctx, futureEvent)
-	if !errors.Is(err, expectedErr) {
+	if !errors.As(err, &errType) || !errors.Is(err, eh.ErrIncorrectEntityVersion) {
+		// if err != expectedErr {
 		t.Error("there should be an error:", err)
 	}
 
@@ -171,15 +166,9 @@ func TestEventHandler_UpdateModelWithVersion(t *testing.T) {
 		Version: 3,
 		Content: "version 1",
 	}
-	expectedErr = Error{
-		Err:           ErrIncorrectProjectedEntityVersion,
-		Projector:     TestProjectorType.String(),
-		Event:         nextEvent,
-		EntityID:      id,
-		EntityVersion: 3,
-	}
+	errType = &Error{}
 	err = handler.HandleEvent(ctx, nextEvent)
-	if !errors.Is(err, expectedErr) {
+	if !errors.As(err, &errType) || !errors.Is(err, ErrIncorrectProjectedEntityVersion) {
 		t.Error("there should be an error:", err)
 	}
 
@@ -362,7 +351,7 @@ func TestEventHandler_LoadError(t *testing.T) {
 
 	err := handler.HandleEvent(ctx, event)
 
-	projectError := Error{}
+	projectError := &Error{}
 	if !errors.As(err, &projectError) || !errors.Is(err, loadErr) {
 		t.Error("there should be an error:", err)
 	}
@@ -389,7 +378,7 @@ func TestEventHandler_SaveError(t *testing.T) {
 
 	err := handler.HandleEvent(ctx, event)
 
-	projectError := Error{}
+	projectError := &Error{}
 	if !errors.As(err, &projectError) || !errors.Is(err, saveErr) {
 		t.Error("there should be an error:", err)
 	}
@@ -416,7 +405,7 @@ func TestEventHandler_ProjectError(t *testing.T) {
 
 	err := handler.HandleEvent(ctx, event)
 
-	projectError := Error{}
+	projectError := &Error{}
 	if !errors.As(err, &projectError) || !errors.Is(err, projectErr) {
 		t.Error("there should be an error:", err)
 	}
diff --git a/eventhandler/saga/eventhandler.go b/eventhandler/saga/eventhandler.go
index 9a329f1f..1057bb01 100644
--- a/eventhandler/saga/eventhandler.go
+++ b/eventhandler/saga/eventhandler.go
@@ -58,17 +58,17 @@ type Error struct {
 }
 
 // Error implements the Error method of the errors.Error interface.
-func (e Error) Error() string {
+func (e *Error) Error() string {
 	return fmt.Sprintf("%s: %s", e.Saga, e.Err)
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e Error) Unwrap() error {
+func (e *Error) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e Error) Cause() error {
+func (e *Error) Cause() error {
 	return e.Unwrap()
 }
 
@@ -89,7 +89,7 @@ func (h *EventHandler) HandlerType() eh.EventHandlerType {
 func (h *EventHandler) HandleEvent(ctx context.Context, event eh.Event) error {
 	// Run the saga which can issue commands on the provided command handler.
 	if err := h.saga.RunSaga(ctx, event, h.commandHandler); err != nil {
-		return Error{
+		return &Error{
 			Err:  err,
 			Saga: h.saga.SagaType().String(),
 		}
diff --git a/eventstore.go b/eventstore.go
index d7d80283..e7b2deee 100644
--- a/eventstore.go
+++ b/eventstore.go
@@ -67,7 +67,7 @@ type EventStoreError struct {
 }
 
 // Error implements the Error method of the errors.Error interface.
-func (e EventStoreError) Error() string {
+func (e *EventStoreError) Error() string {
 	str := "event store: "
 
 	if e.Op != "" {
@@ -100,11 +100,11 @@ func (e EventStoreError) Error() string {
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e EventStoreError) Unwrap() error {
+func (e *EventStoreError) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e EventStoreError) Cause() error {
+func (e *EventStoreError) Cause() error {
 	return e.Unwrap()
 }
diff --git a/eventstore/acceptanece_testing.go b/eventstore/acceptanece_testing.go
index e5c9790e..a94b8cf4 100644
--- a/eventstore/acceptanece_testing.go
+++ b/eventstore/acceptanece_testing.go
@@ -44,7 +44,7 @@ func AcceptanceTest(t *testing.T, store eh.EventStore, ctx context.Context) []eh
 
 	// Save no events.
 	err := store.Save(ctx, []eh.Event{}, 0)
-	eventStoreErr := eh.EventStoreError{}
+	eventStoreErr := &eh.EventStoreError{}
 	if !errors.As(err, &eventStoreErr) || eventStoreErr.Err.Error() != "no events" {
 		t.Error("there should be a event store error:", err)
 	}
@@ -65,7 +65,7 @@ func AcceptanceTest(t *testing.T, store eh.EventStore, ctx context.Context) []eh
 
 	// Try to save same event twice.
 	err = store.Save(ctx, []eh.Event{event1}, 1)
-	eventStoreErr = eh.EventStoreError{}
+	eventStoreErr = &eh.EventStoreError{}
 	if !errors.As(err, &eventStoreErr) || eventStoreErr.Err.Error() != "invalid event version" {
 		t.Error("there should be a event store error:", err)
 	}
@@ -115,7 +115,7 @@ func AcceptanceTest(t *testing.T, store eh.EventStore, ctx context.Context) []eh
 
 	// Load events for non-existing aggregate.
 	events, err := store.Load(ctx, uuid.New())
-	eventStoreErr = eh.EventStoreError{}
+	eventStoreErr = &eh.EventStoreError{}
 	if !errors.As(err, &eventStoreErr) || !errors.Is(err, eh.ErrAggregateNotFound) {
 		t.Error("there should be a not found error:", err)
 	}
diff --git a/eventstore/maintenance_testing.go b/eventstore/maintenance_testing.go
index a2817caa..3edce3f0 100644
--- a/eventstore/maintenance_testing.go
+++ b/eventstore/maintenance_testing.go
@@ -63,7 +63,7 @@ func MaintenanceAcceptanceTest(t *testing.T, store eh.EventStore, storeMaintenan
 	eventWithInvalidVersion := eh.NewEvent(mocks.EventType, &mocks.EventData{Content: "event20"}, timestamp,
 		eh.ForAggregate(mocks.AggregateType, id, 20))
 	err = storeMaintenance.Replace(ctx, eventWithInvalidVersion)
-	eventStoreErr := eh.EventStoreError{}
+	eventStoreErr := &eh.EventStoreError{}
 	if !errors.As(err, &eventStoreErr) || eventStoreErr.Err.Error() != "could not find original event" {
 		t.Error("there should be a event store error:", err)
 	}
diff --git a/eventstore/memory/eventmaintenance.go b/eventstore/memory/eventmaintenance.go
index 39df9b71..3a7e5def 100644
--- a/eventstore/memory/eventmaintenance.go
+++ b/eventstore/memory/eventmaintenance.go
@@ -30,7 +30,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 	aggregate, ok := s.db[id]
 	if !ok {
 		s.dbMu.RUnlock()
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:         eh.ErrAggregateNotFound,
 			Op:          eh.EventStoreOpReplace,
 			AggregateID: id,
@@ -42,7 +42,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 	// Create the event record for the Database.
 	e, err := copyEvent(ctx, event)
 	if err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:         fmt.Errorf("could not copy event: %w", err),
 			Op:          eh.EventStoreOpReplace,
 			AggregateID: id,
@@ -59,7 +59,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 		}
 	}
 	if idx == -1 {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:         fmt.Errorf("could not find original event"),
 			Op:          eh.EventStoreOpReplace,
 			AggregateID: id,
diff --git a/eventstore/memory/eventstore.go b/eventstore/memory/eventstore.go
index 9d5d2315..13ffa367 100644
--- a/eventstore/memory/eventstore.go
+++ b/eventstore/memory/eventstore.go
@@ -69,7 +69,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 	if s.eventHandler != nil {
 		for _, e := range events {
 			if err := s.eventHandler.HandleEvent(ctx, e); err != nil {
-				return eh.EventHandlerError{
+				return &eh.EventHandlerError{
 					Err:   err,
 					Event: e,
 				}
@@ -86,7 +86,7 @@ func (s *EventStore) save(ctx context.Context, events []eh.Event, originalVersio
 	defer s.dbMu.Unlock()
 
 	if len(events) == 0 {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err: fmt.Errorf("no events"),
 			Op:  eh.EventStoreOpSave,
 		}
@@ -101,7 +101,7 @@ func (s *EventStore) save(ctx context.Context, events []eh.Event, originalVersio
 	for i, event := range events {
 		// Only accept events belonging to the same aggregate.
 		if event.AggregateID() != id {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("event has different aggregate ID"),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -112,7 +112,7 @@ func (s *EventStore) save(ctx context.Context, events []eh.Event, originalVersio
 		}
 
 		if event.AggregateType() != at {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("event has different aggregate type"),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -124,7 +124,7 @@ func (s *EventStore) save(ctx context.Context, events []eh.Event, originalVersio
 
 		// Only accept events that apply to the correct aggregate version.
 		if event.Version() != originalVersion+i+1 {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("invalid event version"),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -137,7 +137,7 @@ func (s *EventStore) save(ctx context.Context, events []eh.Event, originalVersio
 		// Create the event record with timestamp.
 		e, err := copyEvent(ctx, event)
 		if err != nil {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("could not copy event: %w", err),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -165,7 +165,7 @@ func (s *EventStore) save(ctx context.Context, events []eh.Event, originalVersio
 		// since loading the aggregate).
 		if aggregate, ok := s.db[id]; ok {
 			if aggregate.Version != originalVersion {
-				return eh.EventStoreError{
+				return &eh.EventStoreError{
 					Err:              fmt.Errorf("invalid original aggregate version, new version: %d", aggregate.Version),
 					Op:               eh.EventStoreOpSave,
 					AggregateType:    at,
@@ -192,7 +192,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 
 	aggregate, ok := s.db[id]
 	if !ok {
-		return nil, eh.EventStoreError{
+		return nil, &eh.EventStoreError{
 			Err:         eh.ErrAggregateNotFound,
 			Op:          eh.EventStoreOpLoad,
 			AggregateID: id,
@@ -203,7 +203,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 	for i, event := range aggregate.Events {
 		e, err := copyEvent(ctx, event)
 		if err != nil {
-			return nil, eh.EventStoreError{
+			return nil, &eh.EventStoreError{
 				Err:              fmt.Errorf("could not copy event: %w", err),
 				Op:               eh.EventStoreOpLoad,
 				AggregateType:    e.AggregateType(),
@@ -233,16 +233,15 @@ func (s *EventStore) Close() error {
 
 // copyEvent duplicates an event.
 func copyEvent(ctx context.Context, event eh.Event) (eh.Event, error) {
-	// Copy data if there is any.
 	var data eh.EventData
+
+	// Copy data if there is any.
 	if event.Data() != nil {
 		var err error
 		if data, err = eh.CreateEventData(event.EventType()); err != nil {
 			return nil, fmt.Errorf("could not create event data: %w", err)
-			// return nil, eh.EventStoreError{
-			// 	Err: fmt.Errorf("could not create event data: %w", err),
-			// }
 		}
+
 		copier.Copy(data, event.Data())
 	}
 
diff --git a/eventstore/mongodb/eventmaintenance.go b/eventstore/mongodb/eventmaintenance.go
index 7ca19fae..7eda35f8 100644
--- a/eventstore/mongodb/eventmaintenance.go
+++ b/eventstore/mongodb/eventmaintenance.go
@@ -35,7 +35,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 	// First check if the aggregate exists, the not found error in the update
 	// query can mean both that the aggregate or the event is not found.
 	if n, err := s.aggregates.CountDocuments(ctx, bson.M{"_id": id}); n == 0 {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:              eh.ErrAggregateNotFound,
 			Op:               eh.EventStoreOpReplace,
 			AggregateType:    at,
@@ -44,7 +44,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 			Events:           []eh.Event{event},
 		}
 	} else if err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:              fmt.Errorf("could not check aggregate existence: %w", err),
 			Op:               eh.EventStoreOpReplace,
 			AggregateType:    at,
@@ -70,7 +70,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 			"$set": bson.M{"events.$": *e},
 		},
 	); err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:              err,
 			Op:               eh.EventStoreOpReplace,
 			AggregateType:    at,
@@ -79,7 +79,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 			Events:           []eh.Event{event},
 		}
 	} else if r.MatchedCount == 0 {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:              fmt.Errorf("could not find original event"),
 			Op:               eh.EventStoreOpReplace,
 			AggregateType:    at,
@@ -104,7 +104,7 @@ func (s *EventStore) RenameEvent(ctx context.Context, from, to eh.EventType) err
 			"$set": bson.M{"events.$.event_type": to.String()},
 		},
 	); err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err: fmt.Errorf("could not update events of type '%s': %w", from, err),
 			Op:  eh.EventStoreOpRename,
 		}
@@ -116,7 +116,7 @@ func (s *EventStore) RenameEvent(ctx context.Context, from, to eh.EventType) err
 // Clear clears the event storage.
 func (s *EventStore) Clear(ctx context.Context) error {
 	if err := s.aggregates.Drop(ctx); err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err: err,
 			Op:  eh.EventStoreOpRename,
 		}
diff --git a/eventstore/mongodb/eventstore.go b/eventstore/mongodb/eventstore.go
index 61e5b198..d73868b2 100644
--- a/eventstore/mongodb/eventstore.go
+++ b/eventstore/mongodb/eventstore.go
@@ -96,7 +96,7 @@ func WithEventHandler(h eh.EventHandler) Option {
 // Save implements the Save method of the eventhorizon.EventStore interface.
 func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersion int) error {
 	if len(events) == 0 {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err: fmt.Errorf("no events"),
 			Op:  eh.EventStoreOpSave,
 		}
@@ -111,7 +111,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 	for i, event := range events {
 		// Only accept events belonging to the same aggregate.
 		if event.AggregateID() != id {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("event has different aggregate ID"),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -122,7 +122,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 		}
 
 		if event.AggregateType() != at {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("event has different aggregate type"),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -134,7 +134,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 
 		// Only accept events that apply to the correct aggregate version.
 		if event.Version() != originalVersion+i+1 {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("invalid event version"),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -147,7 +147,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 		// Create the event record for the DB.
 		e, err := newEvt(ctx, event)
 		if err != nil {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("could not copy event: %w", err),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -169,7 +169,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 		}
 
 		if _, err := s.aggregates.InsertOne(ctx, aggregate); err != nil {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("could not insert: %w", err),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -192,7 +192,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 				"$inc":  bson.M{"version": len(dbEvents)},
 			},
 		); err != nil {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("could not update: %w", err),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -201,7 +201,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 				Events:           events,
 			}
 		} else if r.MatchedCount == 0 {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("invalid original aggregate version, new version %d", originalVersion),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -216,7 +216,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 	if s.eventHandler != nil {
 		for _, e := range events {
 			if err := s.eventHandler.HandleEvent(ctx, e); err != nil {
-				return eh.EventHandlerError{
+				return &eh.EventHandlerError{
 					Err:   err,
 					Event: e,
 				}
@@ -236,7 +236,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 			err = eh.ErrAggregateNotFound
 		}
 
-		return nil, eh.EventStoreError{
+		return nil, &eh.EventStoreError{
 			Err:         err,
 			Op:          eh.EventStoreOpLoad,
 			AggregateID: id,
@@ -250,7 +250,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 		if len(e.RawData) > 0 {
 			var err error
 			if e.data, err = eh.CreateEventData(e.EventType); err != nil {
-				return nil, eh.EventStoreError{
+				return nil, &eh.EventStoreError{
 					Err:              fmt.Errorf("could not create event data: %w", err),
 					Op:               eh.EventStoreOpLoad,
 					AggregateType:    e.AggregateType,
@@ -261,7 +261,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 			}
 
 			if err := bson.Unmarshal(e.RawData, e.data); err != nil {
-				return nil, eh.EventStoreError{
+				return nil, &eh.EventStoreError{
 					Err:              fmt.Errorf("could not unmarshal event data: %w", err),
 					Op:               eh.EventStoreOpLoad,
 					AggregateType:    e.AggregateType,
diff --git a/eventstore/mongodb_v2/eventmaintenance.go b/eventstore/mongodb_v2/eventmaintenance.go
index e599e8cc..2aaa41df 100644
--- a/eventstore/mongodb_v2/eventmaintenance.go
+++ b/eventstore/mongodb_v2/eventmaintenance.go
@@ -35,7 +35,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 
 	sess, err := s.client.StartSession(nil)
 	if err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:              fmt.Errorf("could not start transaction: %w", err),
 			Op:               eh.EventStoreOpSave,
 			AggregateType:    at,
@@ -94,7 +94,7 @@ func (s *EventStore) Replace(ctx context.Context, event eh.Event) error {
 
 		return nil, nil
 	}); err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:              err,
 			Op:               eh.EventStoreOpReplace,
 			AggregateType:    at,
@@ -119,7 +119,7 @@ func (s *EventStore) RenameEvent(ctx context.Context, from, to eh.EventType) err
 			"$set": bson.M{"event_type": to.String()},
 		},
 	); err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err: fmt.Errorf("could not update events of type '%s': %w", from, err),
 			Op:  eh.EventStoreOpRename,
 		}
@@ -131,13 +131,13 @@ func (s *EventStore) RenameEvent(ctx context.Context, from, to eh.EventType) err
 // Clear clears the event storage.
 func (s *EventStore) Clear(ctx context.Context) error {
 	if err := s.events.Drop(ctx); err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err: fmt.Errorf("could not clear events collection: %w", err),
 		}
 	}
 
 	if err := s.streams.Drop(ctx); err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err: fmt.Errorf("could not clear streams collection: %w", err),
 		}
 	}
diff --git a/eventstore/mongodb_v2/eventstore.go b/eventstore/mongodb_v2/eventstore.go
index d765f777..d339c817 100644
--- a/eventstore/mongodb_v2/eventstore.go
+++ b/eventstore/mongodb_v2/eventstore.go
@@ -122,7 +122,7 @@ func WithEventHandler(h eh.EventHandler) Option {
 // Save implements the Save method of the eventhorizon.EventStore interface.
 func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersion int) error {
 	if len(events) == 0 {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err: fmt.Errorf("no events"),
 			Op:  eh.EventStoreOpSave,
 		}
@@ -137,7 +137,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 	for i, event := range events {
 		// Only accept events belonging to the same aggregate.
 		if event.AggregateID() != id {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("event has different aggregate"),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -149,7 +149,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 
 		// Only accept events that apply to the correct aggregate version.
 		if event.Version() != originalVersion+i+1 {
-			return eh.EventStoreError{
+			return &eh.EventStoreError{
 				Err:              fmt.Errorf("invalid event version"),
 				Op:               eh.EventStoreOpSave,
 				AggregateType:    at,
@@ -170,7 +170,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 
 	sess, err := s.client.StartSession(nil)
 	if err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:              fmt.Errorf("could not start transaction: %w", err),
 			Op:               eh.EventStoreOpSave,
 			AggregateType:    at,
@@ -274,7 +274,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 
 		return nil, nil
 	}); err != nil {
-		return eh.EventStoreError{
+		return &eh.EventStoreError{
 			Err:              err,
 			Op:               eh.EventStoreOpSave,
 			AggregateType:    at,
@@ -288,7 +288,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 	if s.eventHandler != nil {
 		for _, e := range events {
 			if err := s.eventHandler.HandleEvent(ctx, e); err != nil {
-				return eh.EventHandlerError{
+				return &eh.EventHandlerError{
 					Err:   err,
 					Event: e,
 				}
@@ -303,7 +303,7 @@ func (s *EventStore) Save(ctx context.Context, events []eh.Event, originalVersio
 func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error) {
 	cursor, err := s.events.Find(ctx, bson.M{"aggregate_id": id})
 	if err != nil {
-		return nil, eh.EventStoreError{
+		return nil, &eh.EventStoreError{
 			Err:         fmt.Errorf("could not find event: %w", err),
 			Op:          eh.EventStoreOpLoad,
 			AggregateID: id,
@@ -315,7 +315,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 	for cursor.Next(ctx) {
 		var e evt
 		if err := cursor.Decode(&e); err != nil {
-			return nil, eh.EventStoreError{
+			return nil, &eh.EventStoreError{
 				Err:         fmt.Errorf("could not decode event: %w", err),
 				Op:          eh.EventStoreOpLoad,
 				AggregateID: id,
@@ -327,7 +327,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 		if len(e.RawData) > 0 {
 			var err error
 			if e.data, err = eh.CreateEventData(e.EventType); err != nil {
-				return nil, eh.EventStoreError{
+				return nil, &eh.EventStoreError{
 					Err:              fmt.Errorf("could not create event data: %w", err),
 					Op:               eh.EventStoreOpLoad,
 					AggregateType:    e.AggregateType,
@@ -338,7 +338,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 			}
 
 			if err := bson.Unmarshal(e.RawData, e.data); err != nil {
-				return nil, eh.EventStoreError{
+				return nil, &eh.EventStoreError{
 					Err:              fmt.Errorf("could not unmarshal event data: %w", err),
 					Op:               eh.EventStoreOpLoad,
 					AggregateType:    e.AggregateType,
@@ -366,7 +366,7 @@ func (s *EventStore) Load(ctx context.Context, id uuid.UUID) ([]eh.Event, error)
 	}
 
 	if len(events) == 0 {
-		return nil, eh.EventStoreError{
+		return nil, &eh.EventStoreError{
 			Err:         eh.ErrAggregateNotFound,
 			Op:          eh.EventStoreOpLoad,
 			AggregateID: id,
@@ -425,7 +425,7 @@ func newEvt(ctx context.Context, event eh.Event) (*evt, error) {
 
 		e.RawData, err = bson.Marshal(event.Data())
 		if err != nil {
-			return nil, eh.EventStoreError{
+			return nil, &eh.EventStoreError{
 				Err: fmt.Errorf("could not marshal event data: %w", err),
 			}
 		}
diff --git a/examples/todomvc/backend/handler/handler_test.go b/examples/todomvc/backend/handler/handler_test.go
index be5b4eb2..bd53d0a5 100644
--- a/examples/todomvc/backend/handler/handler_test.go
+++ b/examples/todomvc/backend/handler/handler_test.go
@@ -224,7 +224,7 @@ func TestDelete(t *testing.T) {
 	cancelTimeout()
 
 	_, err = todoRepo.Find(ctx, id)
-	repoErr := eh.RepoError{}
+	repoErr := &eh.RepoError{}
 	if !errors.As(err, &repoErr) || !errors.Is(err, eh.ErrEntityNotFound) {
 		t.Error("there should be a not found error:", err)
 	}
diff --git a/middleware/commandhandler/async/middleware.go b/middleware/commandhandler/async/middleware.go
index f62dbb5b..90ea5e3a 100644
--- a/middleware/commandhandler/async/middleware.go
+++ b/middleware/commandhandler/async/middleware.go
@@ -23,14 +23,14 @@ import (
 
 // NewMiddleware returns a new async handling middleware that returns any errors
 // on a error channel.
-func NewMiddleware() (eh.CommandHandlerMiddleware, chan Error) {
-	errCh := make(chan Error, 20)
+func NewMiddleware() (eh.CommandHandlerMiddleware, chan *Error) {
+	errCh := make(chan *Error, 20)
 	return eh.CommandHandlerMiddleware(func(h eh.CommandHandler) eh.CommandHandler {
 		return eh.CommandHandlerFunc(func(ctx context.Context, cmd eh.Command) error {
 			go func() {
 				if err := h.HandleCommand(ctx, cmd); err != nil {
 					// Always try to deliver errors.
-					errCh <- Error{err, ctx, cmd}
+					errCh <- &Error{err, ctx, cmd}
 				}
 			}()
 			return nil
@@ -49,16 +49,16 @@ type Error struct {
 }
 
 // Error implements the Error method of the error interface.
-func (e Error) Error() string {
+func (e *Error) Error() string {
 	return fmt.Sprintf("%s (%s): %s", e.Command.CommandType(), e.Command.AggregateID(), e.Err.Error())
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e Error) Unwrap() error {
+func (e *Error) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e Error) Cause() error {
+func (e *Error) Cause() error {
 	return e.Unwrap()
 }
diff --git a/middleware/commandhandler/scheduler/middleware.go b/middleware/commandhandler/scheduler/middleware.go
index d2304d00..168069e2 100644
--- a/middleware/commandhandler/scheduler/middleware.go
+++ b/middleware/commandhandler/scheduler/middleware.go
@@ -24,8 +24,8 @@ import (
 
 // NewMiddleware returns a new async handling middleware that returns any errors
 // on a error channel.
-func NewMiddleware() (eh.CommandHandlerMiddleware, chan Error) {
-	errCh := make(chan Error, 20)
+func NewMiddleware() (eh.CommandHandlerMiddleware, chan *Error) {
+	errCh := make(chan *Error, 20)
 	return eh.CommandHandlerMiddleware(func(h eh.CommandHandler) eh.CommandHandler {
 		return eh.CommandHandlerFunc(func(ctx context.Context, cmd eh.Command) error {
 			// Delayed command execution if there is time set.
@@ -44,7 +44,7 @@ func NewMiddleware() (eh.CommandHandlerMiddleware, chan Error) {
 
 					if err != nil {
 						// Always try to deliver errors.
-						errCh <- Error{err, ctx, cmd}
+						errCh <- &Error{err, ctx, cmd}
 					}
 				}()
 				return nil
@@ -91,16 +91,16 @@ type Error struct {
 }
 
 // Error implements the Error method of the error interface.
-func (e Error) Error() string {
+func (e *Error) Error() string {
 	return fmt.Sprintf("%s (%s): %s", e.Command.CommandType(), e.Command.AggregateID(), e.Err.Error())
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e Error) Unwrap() error {
+func (e *Error) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e Error) Cause() error {
+func (e *Error) Cause() error {
 	return e.Unwrap()
 }
diff --git a/middleware/commandhandler/scheduler/middleware_test.go b/middleware/commandhandler/scheduler/middleware_test.go
index 452dbb8f..ee2f9320 100644
--- a/middleware/commandhandler/scheduler/middleware_test.go
+++ b/middleware/commandhandler/scheduler/middleware_test.go
@@ -103,7 +103,7 @@ func TestMiddleware_Errors(t *testing.T) {
 	if len(inner.Commands) != 0 {
 		t.Error("the command should not have been handled yet:", inner.Commands)
 	}
-	var err Error
+	var err *Error
 	select {
 	case err = <-errCh:
 	case <-time.After(10 * time.Millisecond):
@@ -133,7 +133,7 @@ func TestMiddleware_ContextCanceled(t *testing.T) {
 	if len(inner.Commands) != 0 {
 		t.Error("the command should not have been handled yet:", inner.Commands)
 	}
-	var err Error
+	var err *Error
 	select {
 	case err = <-errCh:
 	case <-time.After(10 * time.Millisecond):
@@ -164,7 +164,7 @@ func TestMiddleware_ContextDeadline(t *testing.T) {
 	if len(inner.Commands) != 0 {
 		t.Error("the command should not have been handled yet:", inner.Commands)
 	}
-	var err Error
+	var err *Error
 	select {
 	case err = <-errCh:
 	case <-time.After(10 * time.Millisecond):
diff --git a/middleware/commandhandler/validate/middleware.go b/middleware/commandhandler/validate/middleware.go
index 320f2fb1..6f92f14b 100644
--- a/middleware/commandhandler/validate/middleware.go
+++ b/middleware/commandhandler/validate/middleware.go
@@ -43,7 +43,7 @@ func NewMiddleware() eh.CommandHandlerMiddleware {
 			// Call the validation method if it exists.
 			if c, ok := cmd.(Command); ok {
 				if err := c.Validate(); err != nil {
-					return Error{err}
+					return &Error{err}
 				}
 			}
 
@@ -59,17 +59,17 @@ type Error struct {
 }
 
 // Error implements the Error method of the error interface.
-func (e Error) Error() string {
+func (e *Error) Error() string {
 	return fmt.Sprintf("invalid command: %s", e.err.Error())
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e Error) Unwrap() error {
+func (e *Error) Unwrap() error {
 	return e.err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e Error) Cause() error {
+func (e *Error) Cause() error {
 	return e.Unwrap()
 }
 
diff --git a/middleware/commandhandler/validate/middleware_test.go b/middleware/commandhandler/validate/middleware_test.go
index 5cd7b426..e95a7019 100644
--- a/middleware/commandhandler/validate/middleware_test.go
+++ b/middleware/commandhandler/validate/middleware_test.go
@@ -52,7 +52,7 @@ func TestMiddleware_WithValidationError(t *testing.T) {
 	e := errors.New("a validation error")
 	c := CommandWithValidation(cmd, func() error { return e })
 	err := h.HandleCommand(context.Background(), c)
-	var validateErr Error
+	validateErr := &Error{}
 	if !errors.As(err, &validateErr) {
 		t.Error("there should be a validate error:", err)
 	}
diff --git a/middleware/eventhandler/async/middleware.go b/middleware/eventhandler/async/middleware.go
index f61976da..7a634aac 100644
--- a/middleware/eventhandler/async/middleware.go
+++ b/middleware/eventhandler/async/middleware.go
@@ -23,8 +23,8 @@ import (
 
 // NewMiddleware returns a new async handling middleware that returns any errors
 // on a error channel.
-func NewMiddleware() (eh.EventHandlerMiddleware, chan Error) {
-	errCh := make(chan Error, 20)
+func NewMiddleware() (eh.EventHandlerMiddleware, chan *Error) {
+	errCh := make(chan *Error, 20)
 	return eh.EventHandlerMiddleware(func(h eh.EventHandler) eh.EventHandler {
 		return &eventHandler{h, errCh}
 	}), errCh
@@ -32,7 +32,7 @@ func NewMiddleware() (eh.EventHandlerMiddleware, chan Error) {
 
 type eventHandler struct {
 	eh.EventHandler
-	errCh chan Error
+	errCh chan *Error
 }
 
 // HandleEvent implements the HandleEvent method of the EventHandler.
@@ -40,7 +40,7 @@ func (h *eventHandler) HandleEvent(ctx context.Context, event eh.Event) error {
 	go func() {
 		if err := h.EventHandler.HandleEvent(ctx, event); err != nil {
 			// Always try to deliver errors.
-			h.errCh <- Error{err, ctx, event}
+			h.errCh <- &Error{err, ctx, event}
 		}
 	}()
 	return nil
@@ -57,16 +57,16 @@ type Error struct {
 }
 
 // Error implements the Error method of the error interface.
-func (e Error) Error() string {
+func (e *Error) Error() string {
 	return fmt.Sprintf("%s: %s", e.Event.String(), e.Err.Error())
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e Error) Unwrap() error {
+func (e *Error) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e Error) Cause() error {
+func (e *Error) Cause() error {
 	return e.Unwrap()
 }
diff --git a/mocks/mocks.go b/mocks/mocks.go
index 58b5f7ec..92deea0d 100644
--- a/mocks/mocks.go
+++ b/mocks/mocks.go
@@ -364,8 +364,8 @@ func (b *EventBus) AddHandler(ctx context.Context, m eh.EventMatcher, h eh.Event
 }
 
 // Errors implements the Errors method of the eventhorizon.EventBus interface.
-func (b *EventBus) Errors() <-chan eh.EventBusError {
-	return make(chan eh.EventBusError)
+func (b *EventBus) Errors() <-chan *eh.EventBusError {
+	return make(chan *eh.EventBusError)
 }
 
 // Close implements the Close method of the eventhorizon.EventBus interface.
diff --git a/namespace/error.go b/namespace/error.go
index 3e022bcc..6271b91b 100644
--- a/namespace/error.go
+++ b/namespace/error.go
@@ -26,16 +26,16 @@ type Error struct {
 }
 
 // Error implements the Error method of the errors.Error interface.
-func (e Error) Error() string {
+func (e *Error) Error() string {
 	return fmt.Sprintf("%s (%s)", e.Err, e.Namespace)
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e Error) Unwrap() error {
+func (e *Error) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e Error) Cause() error {
+func (e *Error) Cause() error {
 	return e.Unwrap()
 }
diff --git a/repo.go b/repo.go
index d6ce26e7..0d327b84 100644
--- a/repo.go
+++ b/repo.go
@@ -101,7 +101,7 @@ type RepoError struct {
 }
 
 // Error implements the Error method of the errors.Error interface.
-func (e RepoError) Error() string {
+func (e *RepoError) Error() string {
 	str := "repo: "
 
 	if e.Op != "" {
@@ -122,11 +122,11 @@ func (e RepoError) Error() string {
 }
 
 // Unwrap implements the errors.Unwrap method.
-func (e RepoError) Unwrap() error {
+func (e *RepoError) Unwrap() error {
 	return e.Err
 }
 
 // Cause implements the github.com/pkg/errors Unwrap method.
-func (e RepoError) Cause() error {
+func (e *RepoError) Cause() error {
 	return e.Unwrap()
 }
diff --git a/repo/acceptance_testing.go b/repo/acceptance_testing.go
index e4b6addc..8b5a01d1 100644
--- a/repo/acceptance_testing.go
+++ b/repo/acceptance_testing.go
@@ -60,7 +60,7 @@ func AcceptanceTest(t *testing.T, repo eh.ReadWriteRepo, ctx context.Context) {
 		CreatedAt: time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC),
 	}
 	err = repo.Save(ctx, entityMissingID)
-	repoErr := eh.RepoError{}
+	repoErr := &eh.RepoError{}
 	if !errors.As(err, &repoErr) || repoErr.Err.Error() != "missing entity ID" {
 		t.Error("there should be a repo error:", err)
 	}
diff --git a/repo/memory/repo.go b/repo/memory/repo.go
index a2065d56..7c88e5f0 100644
--- a/repo/memory/repo.go
+++ b/repo/memory/repo.go
@@ -66,7 +66,7 @@ func IntoRepo(ctx context.Context, repo eh.ReadRepo) *Repo {
 // Find implements the Find method of the eventhorizon.ReadRepo interface.
 func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 	if r.factoryFn == nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err:      ErrModelNotSet,
 			Op:       eh.RepoOpFind,
 			EntityID: id,
@@ -79,7 +79,7 @@ func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 	// Fetch entity.
 	b, ok := r.db[id]
 	if !ok {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err:      eh.ErrEntityNotFound,
 			Op:       eh.RepoOpFind,
 			EntityID: id,
@@ -89,7 +89,7 @@ func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 	// Unmarshal.
 	entity := r.factoryFn()
 	if err := json.Unmarshal(b, &entity); err != nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err:      fmt.Errorf("could not unmarshal: %w", err),
 			Op:       eh.RepoOpFind,
 			EntityID: id,
@@ -102,7 +102,7 @@ func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 // FindAll implements the FindAll method of the eventhorizon.ReadRepo interface.
 func (r *Repo) FindAll(ctx context.Context) ([]eh.Entity, error) {
 	if r.factoryFn == nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: ErrModelNotSet,
 			Op:  eh.RepoOpFindAll,
 		}
@@ -115,7 +115,7 @@ func (r *Repo) FindAll(ctx context.Context) ([]eh.Entity, error) {
 		if b, ok := r.db[id]; ok {
 			entity := r.factoryFn()
 			if err := json.Unmarshal(b, &entity); err != nil {
-				return nil, eh.RepoError{
+				return nil, &eh.RepoError{
 					Err: fmt.Errorf("could not unmarshal: %w", err),
 					Op:  eh.RepoOpFindAll,
 				}
@@ -130,7 +130,7 @@ func (r *Repo) FindAll(ctx context.Context) ([]eh.Entity, error) {
 // Save implements the Save method of the eventhorizon.WriteRepo interface.
 func (r *Repo) Save(ctx context.Context, entity eh.Entity) error {
 	if r.factoryFn == nil {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err: ErrModelNotSet,
 			Op:  eh.RepoOpSave,
 		}
@@ -138,7 +138,7 @@ func (r *Repo) Save(ctx context.Context, entity eh.Entity) error {
 
 	id := entity.EntityID()
 	if id == uuid.Nil {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err: fmt.Errorf("missing entity ID"),
 			Op:  eh.RepoOpSave,
 		}
@@ -150,7 +150,7 @@ func (r *Repo) Save(ctx context.Context, entity eh.Entity) error {
 	// Insert entity.
 	b, err := json.Marshal(entity)
 	if err != nil {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err:      fmt.Errorf("could not marshal: %w", err),
 			Op:       eh.RepoOpSave,
 			EntityID: id,
@@ -185,7 +185,7 @@ func (r *Repo) Remove(ctx context.Context, id uuid.UUID) error {
 		return nil
 	}
 
-	return eh.RepoError{
+	return &eh.RepoError{
 		Err:      eh.ErrEntityNotFound,
 		Op:       eh.RepoOpRemove,
 		EntityID: id,
diff --git a/repo/mongodb/repo.go b/repo/mongodb/repo.go
index 95e9669b..05d46151 100644
--- a/repo/mongodb/repo.go
+++ b/repo/mongodb/repo.go
@@ -105,7 +105,7 @@ func IntoRepo(ctx context.Context, repo eh.ReadRepo) *Repo {
 // Find implements the Find method of the eventhorizon.ReadRepo interface.
 func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 	if r.newEntity == nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err:      ErrModelNotSet,
 			Op:       eh.RepoOpFind,
 			EntityID: id,
@@ -117,7 +117,7 @@ func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 		if err == mongo.ErrNoDocuments {
 			err = eh.ErrEntityNotFound
 		}
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err:      err,
 			Op:       eh.RepoOpFind,
 			EntityID: id,
@@ -130,7 +130,7 @@ func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 // FindAll implements the FindAll method of the eventhorizon.ReadRepo interface.
 func (r *Repo) FindAll(ctx context.Context) ([]eh.Entity, error) {
 	if r.newEntity == nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: ErrModelNotSet,
 			Op:  eh.RepoOpFindAll,
 		}
@@ -138,7 +138,7 @@ func (r *Repo) FindAll(ctx context.Context) ([]eh.Entity, error) {
 
 	cursor, err := r.entities.Find(ctx, bson.M{})
 	if err != nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: fmt.Errorf("could not find: %w", err),
 			Op:  eh.RepoOpFindAll,
 		}
@@ -148,7 +148,7 @@ func (r *Repo) FindAll(ctx context.Context) ([]eh.Entity, error) {
 	for cursor.Next(ctx) {
 		entity := r.newEntity()
 		if err := cursor.Decode(entity); err != nil {
-			return nil, eh.RepoError{
+			return nil, &eh.RepoError{
 				Err: fmt.Errorf("could not unmarshal: %w", err),
 				Op:  eh.RepoOpFindAll,
 			}
@@ -157,7 +157,7 @@ func (r *Repo) FindAll(ctx context.Context) ([]eh.Entity, error) {
 	}
 
 	if err := cursor.Close(ctx); err != nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: fmt.Errorf("could not close cursor: %w", err),
 			Op:  eh.RepoOpFindAll,
 		}
@@ -199,7 +199,7 @@ func (i *iter) Close(ctx context.Context) error {
 // FindCustomIter returns a mgo cursor you can use to stream results of very large datasets
 func (r *Repo) FindCustomIter(ctx context.Context, f func(context.Context, *mongo.Collection) (*mongo.Cursor, error)) (eh.Iter, error) {
 	if r.newEntity == nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: ErrModelNotSet,
 			Op:  eh.RepoOpFindQuery,
 		}
@@ -207,13 +207,13 @@ func (r *Repo) FindCustomIter(ctx context.Context, f func(context.Context, *mong
 
 	cursor, err := f(ctx, r.entities)
 	if err != nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: fmt.Errorf("could not find: %w", err),
 			Op:  eh.RepoOpFindQuery,
 		}
 	}
 	if cursor == nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: fmt.Errorf("no cursor"),
 			Op:  eh.RepoOpFindQuery,
 		}
@@ -232,7 +232,7 @@ func (r *Repo) FindCustomIter(ctx context.Context, f func(context.Context, *mong
 // query from the callback.
 func (r *Repo) FindCustom(ctx context.Context, f func(context.Context, *mongo.Collection) (*mongo.Cursor, error)) ([]interface{}, error) {
 	if r.newEntity == nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: ErrModelNotSet,
 			Op:  eh.RepoOpFindQuery,
 		}
@@ -240,13 +240,13 @@ func (r *Repo) FindCustom(ctx context.Context, f func(context.Context, *mongo.Co
 
 	cursor, err := f(ctx, r.entities)
 	if err != nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: fmt.Errorf("could not find: %w", err),
 			Op:  eh.RepoOpFindQuery,
 		}
 	}
 	if cursor == nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: fmt.Errorf("no cursor"),
 			Op:  eh.RepoOpFindQuery,
 		}
@@ -256,7 +256,7 @@ func (r *Repo) FindCustom(ctx context.Context, f func(context.Context, *mongo.Co
 	entity := r.newEntity()
 	for cursor.Next(ctx) {
 		if err := cursor.Decode(entity); err != nil {
-			return nil, eh.RepoError{
+			return nil, &eh.RepoError{
 				Err: fmt.Errorf("could not unmarshal: %w", err),
 				Op:  eh.RepoOpFindQuery,
 			}
@@ -265,7 +265,7 @@ func (r *Repo) FindCustom(ctx context.Context, f func(context.Context, *mongo.Co
 		entity = r.newEntity()
 	}
 	if err := cursor.Close(ctx); err != nil {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: fmt.Errorf("could not close cursor: %w", err),
 			Op:  eh.RepoOpFindQuery,
 		}
@@ -278,7 +278,7 @@ func (r *Repo) FindCustom(ctx context.Context, f func(context.Context, *mongo.Co
 func (r *Repo) Save(ctx context.Context, entity eh.Entity) error {
 	id := entity.EntityID()
 	if id == uuid.Nil {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err: fmt.Errorf("missing entity ID"),
 			Op:  eh.RepoOpSave,
 		}
@@ -293,7 +293,7 @@ func (r *Repo) Save(ctx context.Context, entity eh.Entity) error {
 		},
 		options.Update().SetUpsert(true),
 	); err != nil {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err:      fmt.Errorf("could not save/update: %w", err),
 			Op:       eh.RepoOpSave,
 			EntityID: id,
@@ -305,13 +305,13 @@ func (r *Repo) Save(ctx context.Context, entity eh.Entity) error {
 // Remove implements the Remove method of the eventhorizon.WriteRepo interface.
 func (r *Repo) Remove(ctx context.Context, id uuid.UUID) error {
 	if r, err := r.entities.DeleteOne(ctx, bson.M{"_id": id.String()}); err != nil {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err:      err,
 			Op:       eh.RepoOpRemove,
 			EntityID: id,
 		}
 	} else if r.DeletedCount == 0 {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err:      eh.ErrEntityNotFound,
 			Op:       eh.RepoOpRemove,
 			EntityID: id,
@@ -324,7 +324,7 @@ func (r *Repo) Remove(ctx context.Context, id uuid.UUID) error {
 // Collection lets the function do custom actions on the collection.
 func (r *Repo) Collection(ctx context.Context, f func(context.Context, *mongo.Collection) error) error {
 	if err := f(ctx, r.entities); err != nil {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err: err,
 		}
 	}
@@ -349,7 +349,7 @@ func (r *Repo) SetEntityFactory(f func() eh.Entity) {
 // Clear clears the read model database.
 func (r *Repo) Clear(ctx context.Context) error {
 	if err := r.entities.Drop(ctx); err != nil {
-		return eh.RepoError{
+		return &eh.RepoError{
 			Err: fmt.Errorf("could not drop collection: %w", err),
 			Op:  eh.RepoOpClear,
 		}
diff --git a/repo/mongodb/repo_test.go b/repo/mongodb/repo_test.go
index 99e0efb4..3a69b38f 100644
--- a/repo/mongodb/repo_test.go
+++ b/repo/mongodb/repo_test.go
@@ -101,7 +101,7 @@ func extraRepoTests(t *testing.T, r *Repo) {
 	result, err = r.FindCustom(ctx, func(ctx context.Context, c *mongo.Collection) (*mongo.Cursor, error) {
 		return nil, nil
 	})
-	repoErr := eh.RepoError{}
+	repoErr := &eh.RepoError{}
 	if !errors.As(err, &repoErr) || repoErr.Err.Error() != "no cursor" {
 		t.Error("there should be a invalid query error:", err)
 	}
@@ -116,7 +116,7 @@ func extraRepoTests(t *testing.T, r *Repo) {
 		// Be sure to return nil to not execute the query again in FindCustom.
 		return nil, nil
 	})
-	repoErr = eh.RepoError{}
+	repoErr = &eh.RepoError{}
 	if !errors.As(err, &repoErr) || repoErr.Err.Error() != "no cursor" {
 		t.Error("there should be a invalid query error:", err)
 	}
diff --git a/repo/tracing/repo.go b/repo/tracing/repo.go
index 00a30b1c..4727dc74 100644
--- a/repo/tracing/repo.go
+++ b/repo/tracing/repo.go
@@ -16,6 +16,7 @@ package tracing
 
 import (
 	"context"
+	"errors"
 
 	"github.com/opentracing/opentracing-go"
 	"github.com/opentracing/opentracing-go/ext"
@@ -60,8 +61,7 @@ func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 	entity, err := r.ReadWriteRepo.Find(ctx, id)
 
 	sp.SetTag("eh.aggregate_id", id)
-	if rrErr, ok := err.(eh.RepoError); err != nil &&
-		!(ok && rrErr.Err == eh.ErrEntityNotFound) {
+	if err != nil && !errors.Is(err, eh.ErrEntityNotFound) {
 		ext.LogError(sp, err)
 	}
 	sp.Finish()
diff --git a/repo/version/repo.go b/repo/version/repo.go
index dbace72c..bb6631d4 100644
--- a/repo/version/repo.go
+++ b/repo/version/repo.go
@@ -16,6 +16,7 @@ package version
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	"github.com/jpillora/backoff"
@@ -75,8 +76,7 @@ func (r *Repo) Find(ctx context.Context, id uuid.UUID) (eh.Entity, error) {
 	_, hasDeadline := ctx.Deadline()
 	for {
 		entity, err := r.findMinVersion(ctx, id, minVersion)
-		if rrErr, ok := err.(eh.RepoError); ok &&
-			(rrErr.Err == eh.ErrIncorrectEntityVersion || rrErr.Err == eh.ErrEntityNotFound) {
+		if errors.Is(err, eh.ErrIncorrectEntityVersion) || errors.Is(err, eh.ErrEntityNotFound) {
 			// Try again for incorrect version or if the entity was not found.
 		} else if err != nil {
 			// Return any real error.
@@ -109,13 +109,13 @@ func (r *Repo) findMinVersion(ctx context.Context, id uuid.UUID, minVersion int)
 
 	versionable, ok := entity.(eh.Versionable)
 	if !ok {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: eh.ErrEntityHasNoVersion,
 		}
 	}
 
 	if versionable.AggregateVersion() < minVersion {
-		return nil, eh.RepoError{
+		return nil, &eh.RepoError{
 			Err: eh.ErrIncorrectEntityVersion,
 		}
 	}
diff --git a/repo/version/repo_test.go b/repo/version/repo_test.go
index 0c0f33c3..f6415378 100644
--- a/repo/version/repo_test.go
+++ b/repo/version/repo_test.go
@@ -67,7 +67,7 @@ func extraRepoTests(t *testing.T, r *Repo, baseRepo *memory.Repo) {
 	// Find with min version without version.
 	ctxVersion := NewContextWithMinVersion(ctx, 1)
 	_, err := r.Find(ctxVersion, simpleModel.ID)
-	repoErr := eh.RepoError{}
+	repoErr := &eh.RepoError{}
 	if !errors.As(err, &repoErr) || !errors.Is(err, eh.ErrEntityHasNoVersion) {
 		t.Error("there should be a model has no version error:", err)
 	}
@@ -90,7 +90,7 @@ func extraRepoTests(t *testing.T, r *Repo, baseRepo *memory.Repo) {
 	// Find with min version, too low.
 	ctxVersion = NewContextWithMinVersion(ctx, 2)
 	_, err = r.Find(ctxVersion, m1.ID)
-	repoErr = eh.RepoError{}
+	repoErr = &eh.RepoError{}
 	if !errors.As(err, &repoErr) || !errors.Is(err, eh.ErrIncorrectEntityVersion) {
 		t.Error("there should be a incorrect model version error:", err)
 	}