Default course settings restrict new users from being added into a course site after the course end date. Teachers will need to change the end date to allow the ability to add additional users.
To change this, go into your course’s Settings.
If you are planning to add a colleague or auditor into the site, you can keep the box for Restrict students from viewing course after course end date checked. This option only affects the Student role inside the site.
Approximately 1 year after the end of the term, academic course sites are set to a read-only state. Teachers will no longer be able to add users or edit the course dates. Please contact the help desk for assistance with these older sites.