I\'m having difficulties with serveral of my VB.Net projects that I have upgraded to Visual Studio 2015. These projects have be upgraded over many years from visual studio 2003
I figured out how to fix it. I went into the project properties, under Assembly and set the Neutral language - in my case to English - United States.
Problem solved!
I could reproduce the error - note: I'm in the UK:
.
Private Sub Form1_Click(sender As Object, e As EventArgs) Handles Me.Click
Dim test As DateTime = Now
Debugger.Break()
End Sub
Run the project and click the form - the watch window will display the error, and the popup over test will not show the date.
I've fixed my projects by removing unnecessary localisation. I guess it was adding English and English UK versions of the resources.
Edit: this worked for the simple cases, but some of the projects I maintain have circular dependencies. Yuck. In this situation, building any of the projects would pull in the unwanted resource dlls from a referenced project. To break the cycle I just deleted the unwanted dlls from the referenced project's bin folder before building, so that they are not copied in. I've 'sent a frown' to microsoft describing this problem. I've spent a day and a half now tidying up the mess...
FYI, I've just committed a fix for this that will ship in VS 2015 Update 2 (see https://github.com/dotnet/roslyn/commit/e683a8438d42d92a3d142ba53f38b33315c7dea2).
Another possible work-around for this issue in the meantime is to strong name sign your app (and the satellite assemblies). The debugger was correctly ignoring the multiple resource dlls in the strong name case but not in the "weak" name case.