Google Classroom Troubleshooting Students > Add Students > Add Students from Google Classroom Troubleshooting > NGLSync Troubleshooting Sometimes problems can occur when syncing your course with Google Classroom. Can't Register Google Classroom StudentsYour course page shows the error message Students cannot be registered in your course until you correct your permission settings or unlink Google Classroom. Google Classroom Access BlockedWhen students try to launch your course from Google Classroom, they see the error message Access blocked: Your institution's admin needs to review NGLSync. Google Classroom Roster Not SyncedIf changes you make to your Google Classroom roster do not appear in your NGLSync roster after a few minutes, refresh your Google Classroom roster.