Reply #1 Top
From the metaverse FAQ stickied in the meta forum:

Metaverse Question # 3:  Error 12 (serial does not match) - what is this and how can I fix it? 
 
     This is generally caused after updating or a re-install.  You probably mistyped your serial number, or left out a character, etc.  You won't be able to fix the save game, unfortunately, and I can't submit games or scores for you.
Reply #2 Top
Thanks for the prompt reply. This means that games started while having the updated serial number for Gal Civ II will be posted normally?
Reply #3 Top
It should. Make sure you created your MV character with the exact same serial as you activated the game with when you patched, and you should be fine.