MySQL Server Has Gone Away!
How to fix MySQL error 'server has gone away' by increasing max_allowed_packet setting.
While using or coding Drupal, if you come across an error to the effect “mysql server has gone away”, right in the middle of a request, you may need to do the following.
Find the my.ini file under MySQL server installation directory (mine is under “data” subdirectory), and in the “[mysqld]” section add the following line (or replace the value if it already exists):
max_allowed_packet=16M
Now restart MySQL server and try again. If it doesn’t work, try a value higher than 16M.