The next step is to alter the "Rewards" table that holds every achievement and Award earned by your users. Do you have an exceptionally large userbase? If so, that may be the cause.
You can try running the following query:
Code:
DELETE FROM dbtech_vbactivity_rewards WHERE feature = 'achievement'
That should help lessen the load on your system while you retry the upgrade
Afterwards, run the Maintenance function under DBTech - vBActivity and recalculate achievements.
Fillip