Plesk is not accessible with the following error:
Warning: Unknown: failed to open stream: No such file or directory in Unknown on line 0
Fatal error: Unknown: Failed opening required 'auth.php' (include_path='.;C:\\php\\pear') in Unknown on line 0
Plesk packages were not properly upgraded due to insufficient disk space.
Free up at least 2.700Mb of free space on disk where Plesk is installed and re-run the upgrade: