When performing Unit Tests in Visual Studio 2015 in debug mode, I stumbled upon the exception UnauthorizedAccessException.
An exception of type System.UnauthorizedAccessException occurred in System.Web.dll but was not handled in user code.
Additional information: Access to path C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO 14.0\COMMON7\IDE\COMMONEXTENSIONS\MICROSOFT\TESTWINDOW\App_Data is denied.
I looked into the folder of the error message but could not see the App_Data in it.
So I try my luck and create the folder ‘App_Data’ => and, voilá, it works 🙂