title: TFS 2015 Builds giving error after migrating from 2012
body: <p>We have migrated from TFS 2012 to TFS 2015, after migrating our builds are not working. We are getting the below error.
  I could not find much on internet on this.
  Please help.</p>
  
  <pre><code>TF215097: An error occurred while initializing a build for build definition \Cockpit\DB.Dev.MetadataDB.Build: 
  Exception Message: Could not load file or assembly 'Microsoft.TeamFoundation, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. (type FileNotFoundException)
  Exception Stack Trace: at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark&amp; stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
  at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark&amp; stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
  at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark&amp; stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
  at System.Reflection.RuntimeAssembly.LoadWithPartialNameInternal(AssemblyName an, Evidence securityEvidence, StackCrawlMark&amp; stackMark)
  at System.Reflection.Assembly.LoadWithPartialName(String partialName)
  at System.Activities.Expressions.AssemblyReference.LoadAssembly(AssemblyName assemblyName)
  at System.Activities.Expressions.AssemblyReference.GetAssembly(AssemblyName assemblyName)
  at Microsoft.VisualBasic.Activities.VisualBasicHelper.Initialize(HashSet`1 refAssemNames, HashSet`1 namespaceImportsNames)
  at Microsoft.VisualBasic.Activities.VisualBasicHelper.Compile[T](String expressionText, CodeActivityPublicEnvironmentAccessor publicAccessor, Boolean isLocationExpression)
  at Microsoft.VisualBasic.Activities.VisualBasicValue`1.CacheMetadata(CodeActivityMetadata metadata)
  at System.Activities.CodeActivity`1.OnInternalCacheMetadataExceptResult(Boolean createEmptyBindings)
  at System.Activities.Activity`1.OnInternalCacheMetadata(Boolean createEmptyBindings)
  at System.Activities.Activity.InternalCacheMetadata(Boolean createEmptyBindings, IList`1&amp; validationErrors)
  at System.Activities.ActivityUtilities.ProcessActivity(ChildActivity childActivity, ChildActivity&amp; nextActivity, Stack`1&amp; activitiesRemaining, ActivityCallStack parentChain, IList`1&amp; validationErrors, ProcessActivityTreeOptions options, ProcessActivityCallback callback)
  at System.Activities.ActivityUtilities.ProcessActivityTreeCore(ChildActivity currentActivity, ActivityCallStack parentChain, ProcessActivityTreeOptions options, ProcessActivityCallback callback, IList`1&amp; validationErrors)
  at System.Activities.ActivityUtilities.CacheRootMetadata(Activity activity, LocationReferenceEnvironment hostEnvironment, ProcessActivityTreeOptions options, ProcessActivityCallback callback, IList`1&amp; validationErrors)
  at System.Activities.Validation.ActivityValidationServices.InternalActivityValidationServices.InternalValidate()
  at Microsoft.TeamFoundation.Build.Workflow.WorkflowHelpers.ValidateWorkflow(Activity activity, ValidationSettings validationSettings)
  at Microsoft.TeamFoundation.Build.Hosting.BuildProcessCache.LoadFromXaml(String workflowXaml, TextExpressionImports textExpressionImports)
  at Microsoft.TeamFoundation.Build.Hosting.BuildControllerWorkflowManager.PrepareRequestForBuild(WorkflowManagerActivity activity, IBuildDetail build, WorkflowRequest request, IDictionary`2 dataContext)
  at Microsoft.TeamFoundation.Build.Hosting.BuildWorkflowManager.TryStartWorkflow(WorkflowRequest request, WorkflowManagerActivity activity, BuildWorkflowInstance&amp; workflowInstance, Exception&amp; error, Boolean&amp; syncLockTaken)
  Inner Exception Details:
  Exception Message: Could not load file or assembly 'Microsoft.TeamFoundation, Version=11.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified. (type FileNotFoundException)
  Exception Stack Trace: 
  </code></pre>