diff --git a/README.md b/README.md
index 18299a54e..d08f2a2d3 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 
 Tinode is *not* XMPP/Jabber. It is *not* compatible with XMPP. It's meant as a replacement for XMPP. On the surface, it's a lot like open source WhatsApp or Telegram.
 
-Version 0.20. This is beta-quality software: feature-complete and stable but probably with a few bugs or missing features. Follow [instructions](INSTALL.md) to install and run or use one of the cloud services below. Read [API documentation](docs/API.md).
+This is beta-quality software: feature-complete and stable but probably with a few bugs or missing features. Follow [instructions](INSTALL.md) to install and run or use one of the cloud services below. Read [API documentation](docs/API.md).
 
 <a href="https://apps.apple.com/us/app/tinode/id1483763538"><img src="docs/app-store.svg" height=36></a> <a href="https://play.google.com/store/apps/details?id=co.tinode.tindroidx"><img src="docs/play-store.svg" height=36></a> <a href="https://web.tinode.co/"><img src="docs/web-app.svg" height=36></a>
 
diff --git a/docs/API.md b/docs/API.md
index dc3a11f94..df93bff05 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -1280,7 +1280,7 @@ Tinode uses `{pres}` message to inform clients of important events. A separate [
 pres: {
   topic: "me", // string, topic which receives the notification, always present
   src: "grp1XUtEhjv6HND", // string, topic or user affected by the change, always present
-  what: "on", // string, what's changed, always present
+  what: "on", // string, action type, what's changed, always present
   seq: 123, // integer, "what" is "msg", a server-issued ID of the message,
             // optional
   clear: 15, // integer, "what" is "del", an update to the delete transaction ID.
@@ -1295,6 +1295,22 @@ pres: {
 }
 ```
 
+The following action types are currently defined:
+
+ * on: topic or user came online
+ * off: topic or user went offline
+ * ua: user agent changed, for example user was logged in with one client, then logged in with another
+ * upd: topic description has changed
+ * tags: topic tags have changed
+ * acs: access permissions have changed
+ * gone: topic is no longer available, for example, it was deleted or you were unsubscribed from it
+ * term: subscription to topic has been terminated, you may try to resubscribe
+ * msg: a new message is available
+ * read: one or more messages have been read by the recipient
+ * recv: one or more messages have been received by the recipient
+ * del: messages were deleted
+
+
 The `{pres}` messages are purely transient: they are not stored and no attempt is made to deliver them later if the destination is temporarily unavailable.
 
 Timestamp is not present in `{pres}` messages.
diff --git a/server/hdl_files.go b/server/hdl_files.go
index 89f4012cf..8a6e74aae 100644
--- a/server/hdl_files.go
+++ b/server/hdl_files.go
@@ -262,7 +262,7 @@ func largeFileReceive(wrt http.ResponseWriter, req *http.Request) {
 	}
 
 	writeHttpResponse(NoErrParams(msgID, "", now, params), nil)
-	logs.Info.Println("media upload: ok", fdef.Location)
+	logs.Info.Println("media upload: ok", fdef.Id, fdef.Location)
 }
 
 // largeFileRunGarbageCollection runs every 'period' and deletes up to 'blockSize' unused files.
diff --git a/server/media/media.go b/server/media/media.go
index e6d8260b9..a3f69a965 100644
--- a/server/media/media.go
+++ b/server/media/media.go
@@ -5,6 +5,7 @@ import (
 	"io"
 	"net/http"
 	"path"
+	"regexp"
 	"strings"
 
 	"github.com/tinode/chat/server/store/types"
@@ -40,6 +41,8 @@ type Handler interface {
 	GetIdFromUrl(url string) types.Uid
 }
 
+var fileNamePattern = regexp.MustCompile(`^[-_A-Za-z0-9]+`)
+
 // GetIdFromUrl is a helper method for extracting file ID from a URL.
 func GetIdFromUrl(url, serveUrl string) types.Uid {
 	dir, fname := path.Split(path.Clean(url))
@@ -48,7 +51,7 @@ func GetIdFromUrl(url, serveUrl string) types.Uid {
 		return types.ZeroUid
 	}
 
-	return types.ParseUid(strings.Split(fname, ".")[0])
+	return types.ParseUid(fileNamePattern.FindString(fname))
 }
 
 // matchCORSOrigin compares origin from the HTTP request to a list of allowed origins.
diff --git a/server/store/types/types.go b/server/store/types/types.go
index 1bea0e9cb..e744dfa86 100644
--- a/server/store/types/types.go
+++ b/server/store/types/types.go
@@ -922,6 +922,9 @@ type Subscription struct {
 
 	// Topic's or user's state.
 	state ObjState
+
+	// This is not a fully initialized subscription object
+	dummy bool
 }
 
 // SetPublic assigns a value to `public`, otherwise not accessible from outside the package.
@@ -1032,6 +1035,16 @@ func (s *Subscription) SetState(state ObjState) {
 	s.state = state
 }
 
+// SetDummy marks this subscription object as only partially intialized.
+func (s *Subscription) SetDummy(dummy bool) {
+	s.dummy = dummy
+}
+
+// IsDummy is true if this subscription object as only partially intialized.
+func (s *Subscription) IsDummy() bool {
+	return s.dummy
+}
+
 // Contact is a result of a search for connections
 type Contact struct {
 	Id       string
diff --git a/server/topic.go b/server/topic.go
index 8020e0986..48355e398 100644
--- a/server/topic.go
+++ b/server/topic.go
@@ -2368,6 +2368,30 @@ func (t *Topic) replyGetSub(sess *Session, asUid types.Uid, authLevel auth.Level
 		} else {
 			// User manages cache. Include deleted subscriptions too.
 			subs, err = store.Users.GetTopicsAny(asUid, msgOpts2storeOpts(req))
+
+			// Returned subscriptions do not contain topics which are online now but otherwise unchanged.
+			// We need to add these topic to the list otherwise the user would see them as offline.
+			selected := map[string]struct{}{}
+			for i := range subs {
+				sub := &subs[i]
+				with := sub.GetWith()
+				if with != "" {
+					selected[with] = struct{}{}
+				} else {
+					selected[sub.Topic] = struct{}{}
+				}
+			}
+
+			// Add dummy subscriptions for missing online topics.
+			for topic, psd := range t.perSubs {
+				_, present := selected[topic]
+				if !present && psd.online {
+					sub := types.Subscription{Topic: topic}
+					sub.SetWith(topic)
+					sub.SetDummy(true)
+					subs = append(subs, sub)
+				}
+			}
 		}
 	case types.TopicCatFnd:
 		// Select public or private query. Public has priority.
@@ -2500,15 +2524,15 @@ func (t *Topic) replyGetSub(sess *Session, asUid types.Uid, authLevel auth.Level
 
 				if !deleted && !banned {
 					if isReader {
-						if sub.GetTouchedAt().IsZero() {
+						touchedAt := sub.GetTouchedAt()
+						if touchedAt.IsZero() {
 							mts.TouchedAt = nil
 						} else {
-							touchedAt := sub.GetTouchedAt()
 							mts.TouchedAt = &touchedAt
 						}
 						mts.SeqId = sub.GetSeqId()
 						mts.DelId = sub.DelId
-					} else {
+					} else if !sub.UpdatedAt.IsZero() {
 						mts.TouchedAt = &sub.UpdatedAt
 					}
 
@@ -2546,7 +2570,9 @@ func (t *Topic) replyGetSub(sess *Session, asUid types.Uid, authLevel auth.Level
 			}
 
 			if !deleted {
-				mts.UpdatedAt = &sub.UpdatedAt
+				if !sub.UpdatedAt.IsZero() {
+					mts.UpdatedAt = &sub.UpdatedAt
+				}
 				if isReader && !banned {
 					mts.ReadSeqId = sub.ReadSeqId
 					mts.RecvSeqId = sub.RecvSeqId
@@ -2554,7 +2580,7 @@ func (t *Topic) replyGetSub(sess *Session, asUid types.Uid, authLevel auth.Level
 
 				if t.cat != types.TopicCatFnd {
 					// p2p and grp
-					if sharer || uid == asUid || subMode.IsAdmin() {
+					if !sub.IsDummy() && (sharer || uid == asUid || subMode.IsAdmin()) {
 						// If user is not a sharer, the access mode of other ordinary users if not accessible.
 						// Own and admin permissions only are visible to non-sharers.
 						mts.Acs.Mode = subMode.String()
diff --git a/server/utils_test.go b/server/utils_test.go
index 5adb48548..345dbb9a4 100644
--- a/server/utils_test.go
+++ b/server/utils_test.go
@@ -28,23 +28,23 @@ func TestStringSliceDelta(t *testing.T) {
 	// - expected outputs: added, removed, intersection
 	cases := [][5][]string{
 		{
-			[]string{"abc", "def", "fff"}, []string{},
-			[]string{}, []string{"abc", "def", "fff"}, []string{},
+			{"abc", "def", "fff"}, {},
+			{}, {"abc", "def", "fff"}, {},
 		},
 		{
 			{}, {}, {}, {}, {},
 		},
 		{
 			{"aa", "xx", "bb", "aa", "bb"}, {"yy", "aa"},
-			{"yy"}, []string{"aa", "bb", "bb", "xx"}, []string{"aa"},
+			{"yy"}, {"aa", "bb", "bb", "xx"}, {"aa"},
 		},
 		{
-			[]string{"bb", "aa", "bb"}, []string{"yy", "aa", "bb", "zzz", "zzz", "cc"},
-			[]string{"cc", "yy", "zzz", "zzz"}, []string{"bb"}, []string{"aa", "bb"},
+			{"bb", "aa", "bb"}, {"yy", "aa", "bb", "zzz", "zzz", "cc"},
+			{"cc", "yy", "zzz", "zzz"}, {"bb"}, {"aa", "bb"},
 		},
 		{
-			[]string{"aa", "aa", "aa"}, []string{"aa", "aa", "aa"},
-			[]string{}, []string{}, []string{"aa", "aa", "aa"},
+			{"aa", "aa", "aa"}, {"aa", "aa", "aa"},
+			{}, {}, {"aa", "aa", "aa"},
 		},
 	}
 
diff --git a/tn-cli/tn-cli.py b/tn-cli/tn-cli.py
index 980059615..27404dfb3 100644
--- a/tn-cli/tn-cli.py
+++ b/tn-cli/tn-cli.py
@@ -202,7 +202,7 @@ def encode_to_bytes(src):
     if src == None:
         return None
     if isinstance(src, str):
-        return src.encode('utf-8')
+        return ('"' + src + '"').encode()
     return json.dumps(src).encode('utf-8')
 
 # Parse credentials