This question has been answered by wintertribe. See the first response.
The upgrade was supposed to add a new column (rank) to the category table, but it looks like it didn't happen. This happens sometimes when you make too big a jump in versions. Setup is supposed to apply all the intermediate upgrades, but sometimes it doesn't happen.
The upgrade was supposed to add a new column (rank) to the category table, but it looks like it didn't happen.
I'm not sure about this since our IT-department did this. I can find out if needed.
Did you copy the dev site to production recently by exporting and importing specific tables?
The category table (modx_categories) should have a 'rank' field, which you may be able to add manually.