Some of our students get the following message, when they click on a lesson
"Could not find lesson pages"
Debug info: Error code: cannotfindpages.
The error also occurs when a student is busy with a lesson, and tries to navigate to a next page.
Moodle 2.9.1. The site has been in use for about three years now and the problem only recently started.
As I have said; it only happens to some students.
Can anyone shed some led as to possible reasons for this?