"Device Cap Reached" error when you enroll an iOS device in Microsoft Intune

This issue occurs if the user tries to enroll more devices than the device enrollment limit allows.

To fix this issue, follow these steps:

1. Open the Intune admin portal, go to Devices > All Devices, and then examine the number of devices that the user has enrolled.
   
   Note You should also ask the affected user to log on to the Intune user portal and examine the devices that they have enrolled. There may be devices that appear in the Intune user portal but not in the Intune admin portal. These devices also count toward the device enrollment limit.
2. Go to Admin > Mobile Device Management > Enrollment Rules, and examine the device enrollment limit. By default, the limit is set to 15. 
3. If the number of devices that are enrolled has reached the limit, remove any unnecessary devices, or increase the device enrollment limit.
   
   Note Because every enrolled device consumes an Intune license, we recommend that you first remove unnecessary devices before you increase the enrollment limit, if that is still necessary.
4. Re-enroll the device.