Just updated to 2.0 from 1.9.2 and had problems this the db update. Get the following error.
After retry a few times, finally worked. But also sometimes get this when using 2.0

SQLSTATE[HY000]: General error: 2006 MySQL server has gone away

Searched internet for the error and found several references for other programs.
Seems to be about the max_allowed_packet size not being large enough. It suggested following change.

[mysqld]
max_allowed_packet=16M

Has anyone got this error and know the fix?