Citrix VDA Gets Unregistered As Soon As App Is Launched

Recently, I have experienced an odd issue which took several days to get to the root cause of it and getting it resolved.

Issue: Citrix VDA Version 1912 CU2 gets unregistered as soon as an app is launched. End user would get an error “Could not open the app”. They had 2 VDAs and this was happening on both VDAs. Delivery Controller was at 1912 CU2 version.

This happened in a multi-tenant Citrix environment where delivery controller was being shared among different clients. It was working fine for all other clients except this one, so it was some thing client specific and /or their VDA(s).

Tried the following to fix it but none of them worked:

Created new VDAs and put the current one in maintenance mode. That worked for few days only and issue reoccurred.
Deleted the VDAs Virtual Machines after deleting the Machine Catalog and Delivery group from the delivery controller.
As per VDA and Delivery controller event logs, there was a communication error between the two so confirmed that and did not see any communication issues.
Opened a case with Citrix Support but they could not find anything, and they were still researching on it in the back end.

Fix: After comparing with other client’s VDAs it was noticed that this client VDAs were Azure joined whereas others were not. But initial thought was that it would not cause this issue. After disjoining the VDA from Azure AD – Restarting Citrix Desktop Service – app launch was successful. It’s been over a week and it’s been working fine now.