Unable to activate Xamarin Unhanded ERROR - Visual Studio 2015 update 2

Question

I try to activate xamarin account on Visual Studo 2015 Update 2 the error is:

System.FormatException: One of the identified items was in an invalid format.
at Xamarin.Components.Ide.Activation.ActivationService.GetErrorWorkflow(LicenseSyncResult[] results, Boolean ignoreSyncErrors)
at Xamarin.Components.Ide.Activation.ActivationService.<GenerateFullWorkflowSequence>d__100.MoveNext()
at Xamarin.Components.Ide.Activation.ActivationDialog.DisplayWorkflowStep(ActivationWorkflowStep step)
at Xamarin.Components.Ide.Activation.ActivationDialog.<>c__DisplayClass11.<StartSpinnerTaskAndScheduleContinuation>b__12(Task t)

Answer 1

Take a look at this discussion in the Xamarin forums. There are listed several common issues. Your question's there as well:

Xamarin for All! Stable Release: Xamarin 4, Cycle 6 – Service Release 3

Quoted from there:

Ensure that you have updated all of your installed Xamarin packages on both Windows and Mac to match the versions listed under "Release Info" below.

Answer 2

If you still having issues, goto Tool Menu , then Options, Under Xamarin, choose Other and then click on Check Update button, You should find an update pending ( 4.0.3.214), download that and try again. It should work.

Answer 3

将Xamarin更新到最新的稳定版对我有用。