Unfortunately we have been getting the following error many times:
FastCGI-stderr: PHP message: Potential coding error - active database transaction detected during request shutdown:
* line 52 of /mod/quiz/processattempt.php: call to moodle_database->start_delegated_transaction()
We are running Moodle version 2.6.2 (Build: 20140310) with PostgreSQL.
This error has caused the database's memory usage to increase dramatically.
I have had a look at this topic https://moodle.org/mod/forum/discuss.php?d=229365 and we have split the quizzes into multiple pages and our session timeout is 4 hours. I also read that this error could be caused by require_login() being called after moodle_database->start_delegated_transaction() (and having looked at the code, require_login is called about 40 lines later), however we have not changed the code because we are unsure if it is the solution and we currently have hundreds of students using the system.
Please help, any advice is appreciated.