I recognized, that the backup functionality throws a lot of errors when using mysql. The most errors are because the naming of the tables are wrong (UPPERCASE instead of lowercase). See this: Error on table “raz1_errors”! Database reported: Tabelle “RAZ1_ERRORS” nicht gefunden Table “RAZ1_ERROR…

Install as new database, when finished copy that one as backup (as fresh install tables) and afterwards restore the old db over it.