Confluence (Error communicating with Confluence: Internal Server Error) is being displayed when trying to create a new user and grant them Confluence application access, or grant an old user application access.

The following fix can be applied by any Confluence Administrator:

1. Go to Global permissions in Confluence.
2. Edit Permissions
3. uncheck all permissions from the affected group (administrators-confluence)
4. Save the permissions
   • The Group will NOT be removed, instead it will remain in place with an option ticked that you removed
5. Keep repeating step 3-4 until the Group no longer is shown on the Global Permissions page.
6. Re-add the group.