Error code: sessionwaiterr: Quiz submit timeout when uploading a recording via PoodLL Qtype

Error code: sessionwaiterr: Quiz submit timeout when uploading a recording via PoodLL Qtype

by William Stewart -
Number of replies: 2

3.3.1+, php 7, mysql 5.6

I've very recently started getting this error that prevents students from submitting their recordings in Moodle Quizes with a PoodLL qtype. But there are never more than 30-40 students doing this during the same hour (not necessarily simultaneously). This doesn't happen on any other tests, only the one which is a single recording answer. Moreover, we've had way more students doing this simultaneously in the past never had this occur in the past that I am aware of.

Debugging Output is:


Debug info: 
Error code: sessionwaiterr
Stack trace:
  • line 1825 of /lib/dml/mysqli_native_moodle_database.php: dml_sessionwait_exception thrown
  • line 175 of /lib/classes/session/database.php: call to mysqli_native_moodle_database->get_session_lock()
  • line ? of unknownfile: call to core\session\database->handler_read()
  • line 42 of /lib/classes/session/handler.php: call to session_start()
  • line 77 of /lib/classes/session/manager.php: call to core\session\handler->start()
  • line 785 of /lib/setup.php: call to core\session\manager::start()
  • line 26 of /config.php: call to require_once()
  • line 31 of /mod/quiz/processattempt.php: call to require_once()

It started happening a couple of times last week and this afternoon with a heavy amount of recordings its been hitting most students. No changes have been made recently other than increasing max_execution_time for php from 30 to 300 for PoodLL documentation receommendations.

Average of ratings: -
In reply to William Stewart

Re: Error code: sessionwaiterr: Quiz submit timeout when uploading a recording via PoodLL Qtype

by Justin Hunt -
Picture of Particularly helpful Moodlers Picture of Plugin developers

Hi William

Of course it could be a Poodll problem, but I think its probably not. It sounds more like a general sessions in the DB, and a busy DB.  Possibly it only occurs on a single question quiz because more students are finishing and submitting their quizzes simultaneously, than were it a longer quiz.

You could try visiting [your moodle url]/admin/settings.php?section=sessionhandling ,  and toggling off DB sessions. And running it for a day to see if it improves. But don't make that change though until nobody is on the site, or they will get logged out.

Perhaps others have more experience with this error than I do though ...

In reply to Justin Hunt

Re: Error code: sessionwaiterr: Quiz submit timeout when uploading a recording via PoodLL Qtype

by William Stewart -

Appreciate the reply, Justin.

I've turned off the db-based sessions. I'll find out if there is any significant difference in about 10 days as its a big national holiday coming up before I'm back and overseeing the next class doing recordings.


Cheers