I have a MultiSite installation, which I tried to automatically upgrade from 3.0.x (don't remember exactly the version) to 3.4. While doing so, I think there was a problem with my FTP account and the automatic upgrade failed. Then I tried a manual upgrade as explained here: http://codex.wordpress.org/Updating_WordPress#Manual_Update
Now my blogs work, but when I go to /wp-admin, I get this error: Fatal error: Class 'WP_List_Table' not found in wp-admin/includes/list-table.php on line 76.
Does anyone have any idea?