This error will only appear when a mobile license has been checked out. If a mobile license has been checked out, check it back in or restart the license service to resolve the issue. To check in the mobile license:
Go to Admin, Administrative Settings, License Management, Manage License.
Select I would like to check in mobile license.
Click Next.
A box will pop out to select the checked-out license.
Select the mobile license.
Click Next.
Click OK.
Restart the license service.
If you have recently added a user to your license, reactivate it to apply the changes.