Thread:Project:Support desk/Sudden PHP Parse error & PHP Fatal Error MWDebug.php & GlobalFunction.php/reply (8)

Upgrading from a minor release should be something as simple as taking a backup and unpack the new files over the old ones. If you were going to upgrade to a major release (1.24.x to 1.25.x for example) then you should unpack the new installation on a new empty directory and move other files needed on the new folder.