May I suggest the responses posted here be added to the Help document to clarify the privileges required as indicated in the Help? ArcGIS Help (10.2, 10.2.1, and 10.2.2)
We are attempting to use arcpy.DisconnectUser before running a nightly compression of a geodatabase. But when running arcpy.DisconnectUser, we are intermittently receiving an error stating that the connection information provided was for a non-administrative user. The geodatabase uses dbo-schema and we have confirmed that the geodatabase administrator is a member of the sysadmin server role.
Our SDE maintenance scripts fail periodically due to this issue similar to this post: https://community.esri.com/thread/180900. SDE is running v10.3.1 with a SQL Server 2012 back-end. The script runs from a VM that has ArcGIS 10.4.1 installed.