Thread:Project:Support desk/Easy way to upgrade from version 1.8 to 2.1?/reply (9)

Yes, the database structure basically changes with each major version. Coming from 1.8 to 1.22 there will be a lot of changes. Every change can be significant. update.php is the script, which is used to apply these changes to your DB.

A way to solve this cleanly is to remove the content in the new DB again and to import it from backup again. Before you do anything, make sure that really the complete database got imported! E.g. the table page obviously was part of an 1.8 installation and so also must be there in the new DB as well! Depending on how you do the import, it might be interrupted in the middle leaving you with an incomplete DB. See Manual:database layout for the tables and columns, which must be there for each version.

Once you have verified everything is there, try running update.php again...