Access to the path "C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\Temporary ASP.NET Files\cbnonreg\fc933fca\bbf91eea" is denied

I got this error because I had turned on all "Common Language Runtime Exceptions" in the "Exception Settings" window of Visual Studio.

This must be one of the exceptions that fires as part of the normal flow of ASP.NET. If that's your problem (or if you don't know what the "Exception Settings" window does and you want to reset it to default) you should probably open the "Exception Settings" window and click the "Restore the list to the default settings" button at the top, or at least uncheck the exceptions you don't want the debugger to break on.

This sounds like a permissions problem. Make sure that the ASPNET account has full access to the Temporary ASP.NET Files folder. If your problems persist, you could also try running The 'aspnet_regiis -i' command to re-install the framework, which should also reset file permissions.

Failing that, you could try using Process Monitor and filtering to the aspnet_wp.exe process to check what the process is trying to do, and update file permissions accordingly.

In my case the error was followed by further exceptions if I had continued e.g. "mscorlib.dll not loaded". Based on this I found the working solution here: https://stackoverflow.com/a/27446877.

"Goto Tools, Options, Debugging, General, Enable Just My Code".

Root cause analysis: I realized that I attempted to test Release config under IIS Express (no debugging then of course) after prior attempts on Debug config. I was also playing with Web.config transform for Release. VS asked me to disable Just My Code on app launch. When I wanted to turn back to Debug, I started to receive referred errors. None of solution proposals from this thread were successful.