Upgrading site from 2.3.2636 to 2.4.2684 I have an older site that has been chugging along nicely so I haven't updated it in a while. I had an issue with an older version of SmartMap that was suddenly causing a 503 on the site so I fixed that and while I was updating things I thought I'd go ahead an update Craft to the latest version. When I do the automatic update I get the following error message and the update fails:

CDbCommand failed to execute the SQL statement: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away


Before I do a manual update I wanted to see if there was something I could do to resolve this and still have the automatic update work.
Probably a timeout on the MySQL side. You could try making a database backup manually and then changing this config value to false before trying the update again: http://buildwithcraft.com/docs/config-settings#backupDbOnUpdate

That way Craft will skip the database backup during the update, saving some time and hopefully preventing a timeout. Just remember to make a backup every time you update from then on though.