When attempting to log in to ArcGIS Pro with an ArcGIS Online account, the following error message is returned:
Error: The account could not be used to sign in because you have exceeded the maximum number of allowed sessions.
The ArcGIS Online account has been used to log in to ArcGIS Pro on three different machines at the same time, and the maximum number of allowed active ArcGIS Pro sessions is three.
Use one of the following options to resolve this issue.
Ensure the ArcGIS Online account is not used on more than three machines at the same time
Note: In some instances, administrators must unassign and reassign the member’s ArcGIS Pro add-on license. Refer to ArcGIS Pro: Assign or unassign an ArcGIS Pro add-on license or extension for more information.
Note: If the methods described above fail, run the repair on ArcGIS Pro.