Fool me once, shame on Visual Studio. Fool me twice -- blog about it.
I'm hitting this problem right now:
The type ‘Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.ExceptionPolicy’ exists in both ‘c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\salestrakng43fff7f669a167\assembly\dl37aaa54d0a834bf_4294c701\Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.DLL’ and ‘c:\WINDOWS\assembly\GAC_MSIL\Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.9.9.9__b45c88aabd6cf9fa\Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.dll’
What is up? If I do a clean build, manually delete the files out of the Temporary ASP.NET Files, then re-build, the files are copied back into the Temporary ASP.NET directory structure and the compile problem happens again.
Turning on Process Monitor shows where the file from the Temporary ASP.NET Files is coming from: the Bin folder of the ASP.NET Web Application.
Delete the files from BOTH the Bin and the Temporary ASP.NET Files takes care of the problem.