Uncaught exception thrown in session handler.

PDOException: SQLSTATE[08S01]: Communication link failure: 1153 Got a packet bigger than 'max_allowed_packet' bytes: UPDATE {sessions} SET uid=:db_update_placeholder_0, cache=:db_update_placeholder_1, hostname=:db_update_placeholder_2, session=:db_update_placeholder_3, timestamp=:db_update_placeholder_4 WHERE ( (sid = :db_condition_placeholder_0) AND (ssid = :db_condition_placeholder_1) ); Array ( [:db_update_placeholder_0] => 1 [:db_update_placeholder_1] => 0 [:db_update_placeholder_2] => [:db_update_placeholder_3] => Wpw4khR1syd0trFnNVSUxDsOs_MtPQ

That gibberish at the end beginning with => goes on for dozens of pages dumped directly onto the page. Any idea what to look into?

1 Answer 1


You likely need to bump up max_allowed_packet in your MySQL instance. That query is likey trying to store a large amount of data. I have never seen this at runtime, though. I have only had problems with this variable when trying to restore backups.

  • I'll try that, but I don't want to bandaid a larger problem. All the CCK fields the view is returning have really short string values. Where could the massive amount of data that's overflowing my packet size be coming from?
    – Joren
    Commented Oct 25, 2011 at 18:39
  • That particular query is trying to save off session data. That could be anything. The only way to debug this is to unserialize the data and see what is in it.
    – mpdonadio
    Commented Oct 25, 2011 at 18:49
  • So paste the entire output into an unserialize function?
    – Joren
    Commented Oct 25, 2011 at 20:19
  • Just double checked this. It is not exactly just serialized data. You need to look at what is being put into the sessions.session column to see what I am talking about.
    – mpdonadio
    Commented Oct 25, 2011 at 21:06
  • Hmm checked my DB and I have a couple session entries. They're both only ~30 or so characters long though.
    – Joren
    Commented Oct 26, 2011 at 0:05

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