Seriously, you made TWO major changes at once (block size and database type) at once... And deployed in production and partially only (because not all people upgraded).

What the hell are the devs thinking? What is the testnet for? Testnet is not only to test userland code, but it is a fine place to test mining code too damnit!

Now know that from now on, you should ALWAYS test stuff like this on Testnet first.