Cannot read configuration file ' trying to read configuration data from file '\\?\', line number '0'

Question

An app pool kept stopping every time it was started and gave this error in the application logs:

The worker process for application pool \'APP_POOL_NA

Answer 1

In my case, the file C:\inetpub\temp\appPools\DefaultAppPool\DefaultAppPool.config got corrupted, and I just could not delete it through all possible means. Then, I just created a new App Pool and moved the application to the new app pool to make it work. Thanks to all the great answers posted here!

Answer 2

If you recently installed the Windows 10 Fall Creators Update, this problem and a solution for it may be covered in this Microsoft knowledge base article. The solution:

• Open an Administrator Command Prompt (not a Powershell prompt)
• Run: net stop WAS /y
• Run: rmdir /s /q C:\inetpub\temp\appPools
• Run: net start W3SVC

Thanks to @weir for reporting this issue.

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This wasn't a permission error in this instance, but it's would be well worth ensuring IIS_IUSRS has access to your site config just in case. See here for steps on how to do this.

This issue appeared to be a virtual directory appeared in the IIS temp files, which was pointing to the wrong place. To fix:

1. Go to the drive your IIS is installed on, eg. C:\inetpub\temp\appPools\
2. Delete the directory (or virtual directory) with the same name as your app pool.
3. Recycle/Start your app pool again.

Answer 3

I have deleted the DefaultAppPool, then I have created a new pool MyAppPool and added applications in there and it worked.

Answer 4

Hey in my case it was the naming of my website.
It was setup as ($webiste$...) with a couple of dots at the end.

After renaming it worked right

Answer 5

Wanted to add that this can also manifest if the drive the config file is located on is full. We just found that out today and freeing up space and restarting the application pool fixed it.