ArcGIS Online: This user type has been over-assigned

Error Message

Attempting to log in to ArcGIS Online fails and returns the following error message:

Error:   
This user type has been over-assigned
Go to the Members tab to manage members with this user type.

Cause

• The user type has exceeded the limit of assigned licenses. Refer to ArcGIS Online: User types for more information.
• The organization does not have enough available entitlements to assign this user type because the existing user type entitlement has expired.

Solution or Workaround

These solutions must be performed by the organization's administrator. Depending on the cause, the workarounds provided are applicable.

• Reassign the member to a different available user type. Refer to ArcGIS Online: Change user types for instructions.
• Remove or reassign members with expired memberships to free up available user type licenses. Refer to ArcGIS Online: Delete members for instructions.

Note: 
Ensure all content owned by the specific member is bulk transferred to a new owner before deleting a member. Refer to ArcGIS Online: Transfer all content owned by specific members for instructions.

• Purchase additional specific user type licenses through My Esri. Refer to ArcGIS Online: Manage licenses for more information.
• Renew the ArcGIS Online organization subscription. Refer to ArcGIS Online: View status dashboard for more information.