The Deploy test agent task in TFS release definition fails with the below exception:

> 
> Unhandled Exception:
>  System.Management.Automation.PSInvalidOperationException: The
>  WriteObject and WriteError methods cannot be called from outside the
>  overrides of the BeginProcessing, ProcessRecord, and EndProcessing
>  methods, and they can only be called from within the same thread.
>  Validate that the cmdlet makes these calls correctly, or contact
>  Microsoft Customer Support Services. 2017-06-16T08:49:49.9634068Z  
> 
>  at
>  System.Management.Automation.MshCommandRuntime.ThrowIfWriteNotPermitted(Boolean
>  needsToWriteToPipeline) 2017-06-16T08:49:49.9634068Z at
>  System.Management.Automation.MshCommandRuntime.WriteHelper\_ShouldWrite(ActionPreference
>  preference, ContinueStatus lastContinueStatus)
>  2017-06-16T08:49:49.9634068Z at
>  System.Management.Automation.MshCommandRuntime.WriteWarning(WarningRecord
>  record, Boolean overrideInquire) 2017-06-16T08:49:49.9634068Z at
>  System.Management.Automation.Cmdlet.WriteWarning(String text)
>  2017-06-16T08:49:49.9634068Z at
>  Microsoft.TeamFoundation.DistributedTask.Task.DistributedTestAutomation.Logger.WriteWarning(String
>  message) 2017-06-16T08:49:49.9634068Z at
>  Microsoft.TeamFoundation.DistributedTask.Task.DistributedTestAutomation.TestAgentDownloader.wc\_DownloadFileCompleted(Object
>  sender, AsyncCompletedEventArgs e) 2017-06-16T08:49:49.9634068Z at
>  System.Net.WebClient.OnDownloadFileCompleted(AsyncCompletedEventArgs
>  e) 2017-06-16T08:49:49.9634068Z at
>  System.Threading.ExecutionContext.RunInternal(ExecutionContext
>  executionContext, ContextCallback callback, Object state, Boolean
>  preserveSyncCtx) 2017-06-16T08:49:49.9634068Z at
>  System.Threading.ExecutionContext.Run(ExecutionContext
>  executionContext, ContextCallback callback, Object state, Boolean
>  preserveSyncCtx) 2017-06-16T08:49:49.9634068Z at
>  System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
>  2017-06-16T08:49:49.9634068Z at
>  System.Threading.ThreadPoolWorkQueue.Dispatch()
>  2017-06-16T08:49:55.4477257Z ##[error]PowerShell script completed with
>  255 errors.
> 
> 
> 

The task executes successfully if the Update test agent check box is not checked. 
 Solution mentioned here <https://github.com/Microsoft/vsts-tasks/issues/2964> and <https://social.msdn.microsoft.com/Forums/sqlserver/en-US/dae4c62d-cd23-40ad-83cf-2555d37c0bb9/test-agent-deployment-failing?forum=tfsbuild> does not seems to work either