Package installation fails trying to delete PowerShell.zip

[michaellwest]

You may encounter an issue when installing with the following message:

Background process failed: Failed to delete the file 'D:\Sites\scms\sitecore\shell\Themes\Standard\PowerShell.zip'

As seen in the log file:

ManagedPoolThread #6 10:39:31 ERROR Installation failed: System.Exception: Background process failed: Failed to delete the file 'D:\Sites\scms\sitecore\shell\Themes\Standard\PowerShell.zip' ---> System.Exception: Failed to delete the file 'D:\Sites\scms\sitecore\shell\Themes\Standard\PowerShell.zip' ---> System.IO.IOException: The process cannot access the file 'D:\Sites\scms\sitecore\shell\Themes\Standard\PowerShell.zip' because it is being used by another process.

[michaellwest]

This issue appears to prevent any file in the folder from getting deleted.

The IIS Worker process has locked the folder "$($AppPath)\sitecore\shell\Themes\Standard\"

[michaellwest]

The easiest fix is to stop the w3wp.exe for that given Sitecore instance and then manually delete the zip.

[michaellwest]

Another easy fix is to simply skip the item during package installation when the confirmation dialog appears.