What causes 'The process cannot access the file ... *.pdb' when compiling a MAUI project in Release mode?

Question

• Visual Studio: Version 17.6.0 Preview 3.0
• Framework: 8.0.0-preview.1.23110.8
• Operating System: Windows 11 Enterprise Insider Preview Edition; Version 22H2; OS Build 25336.1000

I am getting this endless compile errors of:
System.IO.IOException: The process cannot access the file 'obj\Release\net8.0-android\android\assets<filename>.pdb' because it is being used by another process.

To give you an example of *pdb files, I had ExoPlayer.pdb and Xamarin.Firebase.Iid.pdb.
When ExoPlayer.pdb was flagged, I unistalled the CommunityToolkit.Maui.MediaElement package if compilation succeeds, but another one popped up -- Xamarin.Firebase.Iid.pdb.

What causes these errors, and what is a workaround?

Answer 1

.pdb (debug reference) files are created as part of the build. the error indicates some process has the old file open, so a new one can not be created. you could try to delete the folder first, but it may fail for the same reason. exit programs til the delete works. you can use the openfiles utility to detect which process has the file open:
https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/openfiles.

note: will need to run the command as admin