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

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.