We are currently using CiviCRM 4.6.3 with the CiviEvent module with PayPal Standard. (But this has been happening in previous versions.)
We intermittently have registrations for events that are marked as pending, even after PalPal has completed the transaction and sent PalPal's notification email.
What I have noticed about the one's that remain pending, is that the IPN Notification url seems to be incomplete.
So when CiviCRM receives the 'bad' notification from PayPal, CiviCRM responds with a '200' and PayPal is happy. But then CiviCRM can't find the registration. All CiviCRM logs is
» 25 Aug 2015 04:37:22.157 Aug 25 04:37:21 [info] $Fatal Error Details = Array
» 25 Aug 2015 04:37:22.157 (
» 25 Aug 2015 04:37:22.157 [message] => Could not find valid value for id
» 25 Aug 2015 04:37:22.157 [code] =>
» 25 Aug 2015 04:37:22.157 )
This seems like it would have had to happen at the time the payment was submitted to PayPal.
Has anyone else experienced this?