The VDA machines are hanging during logon and log-off, during the Citrix loading Profile management phase, for multiple users. Multiple VDA machines are affected. If the UPM service is stopped or process killed, the logon/logoff process runs smoothly and no issues logging onto the desktop. Checked the permission settings on the UPM store and the specific user/System account has Full control NTFS permissions as well as the required Share permissions. In the UPM log, for one of the users, can see the following error logged: 

1. Remove the SID for the affected user from the registry.
2. Verify AV exclusions are in place. Check for any Locked file in Pending area of UPM profile, and delete it if present.
3. Refresh the Group policy cache. With a new UPM profile, you will be able to load Citrix profile management and login to the VDA desktop without any issues.