Please could we have something added to the upgrader that checks at the beginning what columns should be added and whether they have already been added for whatever reason and they shouldnt be there yet. To explain a bit further. There are 3 posts so far of people who's attach in conversations would not work. This was due to a modification that had added a column that xenforo 1.1 was to add, so because we uninstalled the attachment modification after upgrading it then removed a column that is required by 1.1. Suggestion: Check version currently being used Check what columns are to be added If any of them columns exist before upgrade, there is a problem so therefore error stating x column on x table has already been added to the database. Alternative: Check on install of a modification if any SQL statement is inserting a column/table using xf naming convention. On finding, error and state as much I think this may save a fair amount of headache on upgrade, and also save you guys a fair amount of support that is not really needed.