- Ensure debug mode is on
- Browse to: Site administration > Users > Permissions > Define roles
- Edit the student role (click the cog)
- Change the role archetype to "Teacher (editing)
- Go back to the main site administration page - you should see a bunch of errors
The issues seems to be that many enrolment plugins have this in their settings.php:
When no role has the student archetype, then $student is not an object and $student->id fails.