Problem Statement: CSS Web Applications return a 500 Internal Server error on load.
Cause: The ASP.NET Dynamic Compilation of the affected CSS web application is corrupt or out of date.
1.Restart IIS by calling "IISReset" from an elevated command prompt to unlock the server side .NET cache.
2.Navigate to "C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files" (v1.1.4322 for older builds).
3.Delete the folder that corresponds with the non-functioning web application. For example if the CSS Reporter is the issue, the "ers.net_apps_reporter" folder would be deleted.
When the web page is reloaded for the first time there will be a slight delay as the cache is rebuilt.