by Stephen Bloomer.
We recently upgraded to Moodle 2.6.4 (Build: 20140714) from an early version of 2.6.3. We now have an issue with several assignment which when we try and access it we get a white page with the following error
Fatal error: Interface 'question_usage_observer' not found in C:\moodle\question\engine\datalib.php on line 1014
Our environment is
Front End Server - Windows 2008 R2, IIS and recently upgraded PHP 5.5.11
Back end server - Windows 2008 R2, MySQL 5.1.50
Any ideas on where I could look to fix this? I have searched the error and I could not find anything like this.
Thanks