Thread:Project:Support desk/Upgrade from 1.11 to 1.22 : Blank Page & Nothing can be seen/reply (2)

You should't have StartProfiler there in the first place, so maybe you're not following the recommendations made in Manual:Upgrading about not unpacking the new files over the old ones.

You should unpack the new version on an empty directory as the instructions say.

Since 1.11 is quite old, instead of copying LocalSettings.php from the old one, it would be safer to run the installer without LocalSettings.php (you can specify the same database, etc, and it will upgrade it), and then manually merge any customizations from your old LocalSettings.php to the new one, probably checking first if those configuration settings are still applicable.