Wrong file, ASP.NET. Thanks anyways.

The other day, on a test server, ASP.NET was giving the following message:

Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0016: Could not write to output file 'c:\WINDOWS\Microsoft.NET\Framework\v1.1.4322\Temporary ASP.NET Files\somepath\10d62725\cb6c7d34\k_kdx1bc.dll' -- 'Access is denied. '

Of course, it wasn't quite that simple. There was no problem accessing that folder, as FILEMON from Sysinternals verified when I set the filter to "Temporary ASP.NET Files". So I then set the filter to CSC.EXE, and noted that it was failing with ACCESS DENIED on C:\Windows\Temp\RES6.TMP running under NT AUTHORITY\NETWORK SERVICE. In the C:\Windows folder, there was a TEMP folder, and a TEMP.DELETETHIS folder. The ACL on the TEMP.DELETETHIS folder had an ACE for NETWORK SERVICE, but the ACL on the TEMP folder did not. The creation date of the new TEMP folder was roughly 1 week ago. So it appears that the installation of ASP.NET added an ACE on the original TEMP folder that would allow ASP.NET / NETWORK SERVICE to do what it needed to do. However, when someone decided they wanted a new TEMP folder on the server, the new TEMP folder inherited the permissions from WINDOWS and as such an ACE for NETWORK SERVICE was not placed on the new folder. Renaming TEMP to TEMP.HOLD and renaming TEMP.DELETETHIS back to TEMP solved the problem. Definitely an argument for better change control on the servers, as well as potentially further restricting access. But much of that is beyond my control...

At any rate... the first hit in a google for CS0016 takes you to the MSKB which almost nails it on the head, but in this case winds up kind of bending the nail so you have to take the hammer and try to pound the nail upright again, and then... er... nevermind.