Using CiviCRM 5.7.2, using Drupal 7.61.

We use CiviEvents and have registrations turned on and confirmation emails enabled. Over the last month a few users have reported not receiving confirmation emails and I was able to replicate this myself today.

Essentially, the user fills in their details and then get a 500 error and no confirmation screen or confirmation email. However their registration pulls through on the back-end (I can see they registered for the event on their user on CiviCRM and I see them as a registrant on CiviEvent). But even though this is pulling through, it's not triggering the confirmation email to be sent to the registrant.

It looks like this happens at random - has happened to about 4% of our recent registrants in the last month. It causes a lot of frustration on their end and a poor user experience so would love to work out why it happens and if there's anything I can do to fix this.

Let me know if you need any more information or if this isn't clear.


EDIT: It just happened again. User gets redirected to [DOMAIN].com/civicrm/event/register. This happens after the "Confirm your registration details" screen.

EDIT 2: These are the two errors I see in Drupal's Error Log

Warning: Unknown: Cannot call session save handler in a recursive manner in main() (line of ).


Warning: Unknown: Failed to write session data using user defined save handler. (session.save_path: /opt/alt/php71/var/lib/php/session) in main() (line of ).

I have no idea what this means, can anyone assist?

  • I have just begun investigating such an error. Unfortunately, it seems that you may have more info than I've got. I will add that credit cards did process, but the event Notify CC addresses did not receive e-mails either. Civi 5.8.2, WP 5.0.3, MariaDB, PHP7
    – G H
    Commented Jan 23, 2019 at 2:44
  • what payment processors are you both using?
    – petednz - fuzion
    Commented Jan 23, 2019 at 3:00
  • @petednz-fuzion using Paypal but this event doesn't have payment enabled
    – josh
    Commented Jan 23, 2019 at 3:23
  • 2
    The 500 error should be getting logged somewhere, drupal watchdog logs or CiviCRM logs, or PHP error log. Find out what is causing the 500 error and that's likely to give you a big clue where it is going wrong. Commented Jan 23, 2019 at 9:45
  • Thanks @MatthewWire, I've just edited in the error messages I found in drupal watchdog logs. I have no idea how to interpret these though, can anyone help? Tried to do some research on it but wasn't able to find any relevant information.
    – josh
    Commented Jan 29, 2019 at 23:38

1 Answer 1


Went into php.ini and replaced the session.save_path parameter from




And it looks like that's done the trick!

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