Thread:Project:Support desk/Easy way to upgrade from version 1.8 to 2.1?/reply (7)

You do not have to remove all extensions, which do not work properly. For the extension CategoryWatch, the last version seems to be from 2011; likely that it also is broken nowadays.

I guess that you have new MySQL credentials and that in LocalSettings.php you are still using the old ones making MediaWiki think you want to start with a new installation. That's why you see only the default stuff in your installation. Make sure to fix the database username, host and password in LocalSettings.php and then try running update.php again. It should then update the correct database. ;-)