"CS0016: Could not write to output file" error when starting an app in IIS 7

Question

I am running Windows 7, and am not usually a developer in this setting, and have recently built a WCF Rest Service in C#, that I'm now trying to deploy to IIS just on my local machine. After much wrangling, I setup up the application, but when I navigate to the application, I get an error message: Compilation Error

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\Framework64\v4.0.30319\Temporary ASP.NET Files\scom_sibyll\8c0b945e\9329016\App_global.asax.eagmqgcd.dll' -- 'Access is denied. '

I have hunted the web to the best of my ability, and have changed the permissions on the Temporary ASP.NET Files fodler to allow the Network Service account full rights, and done the same with the Temp folder. It copies a number of files before failing, so it has write permissions presumably, so I checked the permissions to read from my source folder, and that is working as well. I additionally noted it's crapping out when it tries to to cache the DLL file, and tried turning off my Antivirus protection, as well as turning off UAC, just to see if I could figure out what is blocking this from occurring. I'm fresh out of ideas now. Anybody have any suggestions?

Answer 1

For those looking here as I did, if the accepted answer doesn't resolve the issue you might try following this article: http://lordzoltan.blogspot.com/2011/02/aspnet-2-and-4-default-application-pool.html

In summary, it seems that the same error is sometimes displayed when the app pool user doesn't have access to the %TMP%/%TEMP% folder.

You'll need to grant IIS_IUSRS read and modify access over the temp folder of the user the app pool is running as.

This could either be the temp folder in the app pool user's profile, e.g. c:\Windows\ServiceProfiles\NetworkService\AppData\Local\Temp, or the system temp folder at c:\windows\temp.

Setting this up this resolved the issue for me.