diff --git a/src/MigrationTools.Clients.AzureDevops.Rest/Endpoints/AzureDevOpsEndpoint.cs b/src/MigrationTools.Clients.AzureDevops.Rest/Endpoints/AzureDevOpsEndpoint.cs
index bc4c45be6..f46cff043 100644
--- a/src/MigrationTools.Clients.AzureDevops.Rest/Endpoints/AzureDevOpsEndpoint.cs
+++ b/src/MigrationTools.Clients.AzureDevops.Rest/Endpoints/AzureDevOpsEndpoint.cs
@@ -95,7 +95,7 @@ private UriBuilder GetUriBuilderBasedOnEndpointAndType<DefinitionType>()
             }
             else
             {
-                builder.Query = "api-version=5.1-preview.1";
+                builder.Query = "api-version=5.1-preview";
             }
             return builder;
         }
@@ -103,8 +103,10 @@ private UriBuilder GetUriBuilderBasedOnEndpointAndType<DefinitionType>()
         /// <summary>
         /// Generic Method to get API Definitions (Taskgroups, Variablegroups, Build- or Release Pipelines)
         /// </summary>
-        /// <typeparam name="DefinitionType">Type of Definition. Can be: Taskgroup, Build- or Release Pipeline</typeparam>
-        /// <returns>List of API Definitions </returns>
+        /// <typeparam name="DefinitionType">
+        /// Type of Definition. Can be: Taskgroup, Build- or Release Pipeline
+        /// </typeparam>
+        /// <returns>List of API Definitions</returns>
         public async Task<IEnumerable<DefinitionType>> GetApiDefinitionsAsync<DefinitionType>()
             where DefinitionType : RestApiDefinition, new()
         {
@@ -169,7 +171,7 @@ public async Task<List<Mapping>> CreateApiDefinitionsAsync<DefinitionType>(IEnum
                 var responseContent = await result.Content.ReadAsStringAsync();
                 if (result.StatusCode != HttpStatusCode.OK)
                 {
-                    Log.LogError("Error migrating {DefinitionType} {DefinitionName}. Please migrate it manually. {ErrorText}", typeof(DefinitionType).Name, definitionToBeMigrated.Name, responseContent);
+                    Log.LogError("Error migrating {DefinitionType}: {DefinitionName}. Please migrate it manually. {ErrorText}", typeof(DefinitionType).Name, definitionToBeMigrated.Name, responseContent);
                     continue;
                 }
                 else
@@ -181,7 +183,6 @@ public async Task<List<Mapping>> CreateApiDefinitionsAsync<DefinitionType>(IEnum
                         SourceId = definitionToBeMigrated.Id,
                         TargetId = targetObject.Id
                     });
-
                 }
             }
             Log.LogInformation("{MigratedCount} of {TriedToMigrate} {DefinitionType}(s) got migrated..", migratedDefinitions.Count, definitionsToBeMigrated.Count(), typeof(DefinitionType).Name);
diff --git a/src/MigrationTools.Clients.AzureDevops.Rest/Processors/AzureDevOpsPipelineProcessor.cs b/src/MigrationTools.Clients.AzureDevops.Rest/Processors/AzureDevOpsPipelineProcessor.cs
index 9e4941671..5dd3b90ef 100644
--- a/src/MigrationTools.Clients.AzureDevops.Rest/Processors/AzureDevOpsPipelineProcessor.cs
+++ b/src/MigrationTools.Clients.AzureDevops.Rest/Processors/AzureDevOpsPipelineProcessor.cs
@@ -67,7 +67,8 @@ private void EnsureConfigured()
         }
 
         /// <summary>
-        /// Executes Method for migrating Taskgroups, Variablegroups or Pipelines, depinding on what is set in the config.
+        /// Executes Method for migrating Taskgroups, Variablegroups or Pipelines, depinding on what
+        /// is set in the config.
         /// </summary>
         private async System.Threading.Tasks.Task MigratePipelinesAsync()
         {
@@ -111,8 +112,9 @@ private async System.Threading.Tasks.Task MigratePipelinesAsync()
         private IEnumerable<Mapping> FindExistingMappings<DefintionType>(IEnumerable<DefintionType> sourceDefinitions, IEnumerable<DefintionType> targetDefinitions, List<Mapping> newMappings)
             where DefintionType : RestApiDefinition, new()
         {
-            // This is not safe, because the target project can have a taskgroup with the same name but with different content
-            // To make this save we must add a local storage option for the mappings (sid, tid)
+            // This is not safe, because the target project can have a taskgroup with the same name
+            // but with different content To make this save we must add a local storage option for
+            // the mappings (sid, tid)
             var alreadyMigratedMappings = new List<Mapping>();
             var alreadyMigratedDefintions = targetDefinitions.Where(t => newMappings.Any(m => m.TargetId == t.Id) == false).ToList();
             foreach (var item in alreadyMigratedDefintions)
@@ -187,7 +189,7 @@ private async Task<IEnumerable<Mapping>> CreateBuildPipelinesAsync(IEnumerable<M
                     }
                 }
 
-                if (VariableGroupMapping is not null)
+                if (VariableGroupMapping is not null && definitionToBeMigrated.VariableGroups is not null)
                 {
                     foreach (var variableGroup in definitionToBeMigrated.VariableGroups)
                     {
@@ -206,7 +208,6 @@ private async Task<IEnumerable<Mapping>> CreateBuildPipelinesAsync(IEnumerable<M
                         }
                     }
                 }
-
             }
             var mappings = await Target.CreateApiDefinitionsAsync<BuildDefinition>(definitionsToBeMigrated.ToList());
             mappings.AddRange(FindExistingMappings(sourceDefinitions, targetDefinitions, mappings));
@@ -348,14 +349,14 @@ private void UpdateTaskGroupId(ReleaseDefinition definitionToBeMigrated, IEnumer
                 {
                     foreach (var WorkflowTask in deployPhase.WorkflowTasks)
                     {
-                        if (WorkflowTask.DefinitionType.ToLower() != "metaTask".ToLower())
+                        if (WorkflowTask.DefinitionType != null && WorkflowTask.DefinitionType.ToLower() != "metaTask".ToLower())
                         {
                             continue;
                         }
                         var mapping = TaskGroupMapping.FirstOrDefault(d => d.SourceId == WorkflowTask.TaskId.ToString());
                         if (mapping == null)
                         {
-                            Log.LogWarning("Can't find taskgroup {TaskGroupId} in the target collection.", WorkflowTask.TaskId);
+                            Log.LogWarning("Can't find taskgroup {TaskGroupName} in the target collection.", WorkflowTask.Name);
                         }
                         else
                         {