Thread:Project:Support desk/maintenance/update.php fails with "Cannot redeclare class FakeMaintenance"/reply (4)

You should unpack the new installation files on a new folder and only copy/move/merge the old customized files and upload directory to the new location as needed, changing the published directory to the new one. That would prevent spurious errors like those because old files are conflicting with new ones. Read Manual:Upgrading for more instructions.