Reason: An error occurred while zipping 'C:\Users\Server\Desktop\server\.\world\session.lock'

Message: The process cannot access the file because another process has locked a portion of the file

Because of this, I am not able to make a backup. It usually makes it 60% - 70% of the way before outputting this error.

I have tried deleting the session.lock file but it is essential for running the server. It can be found in the world nether and end folder.