I have faced today a problem in the new Citrix XenApp 6.5 farm that I build for the client. From early morning users reported problems with reconnection to the published desktop. The below message was shown to the users:
I have limited number of instances that user can launch to one for published desktop but still user should be reconnected to the previous session that is still active on one of the XenApp servers.
Also new users were not able to launch published desktop but in this case the session just hanged on the “Preparing your desktop” screen or published desktop wallpaper without any other icons on it.
Quick check and it occurred that problem was happening on one server to which Zone Data Collector was directing all new connections. I’ve removed the server from load balancing group that publishes desktop for end users and killed all hanged sessions on it. When me and my colleague were logging with RDP session to the server the Receiver installed on it crashed during startup. First thought: print drivers!
We launched the Event Viewer and checked System log. Red was a main color and all errors were pointing to the CPSVC.exe – Citrix Print Manager Service that couldn’t start.
Now I was sure that problem is related to the print drivers and my second thought was that for sure we have a lot of HP print drivers installed on that server. It took only few seconds to check that in the Devices and Printers console. Seven different legacy HP print drivers were present on the server. My colleague did a quick “googling” and found very interesing article:
Another look on the Services and we found two mentioned in the article HP related services running on the server:Net Driver HPZ12 and PML Driver HPZ12. Some more information about them you can find here:
Long story short – they are not needed on Citrix server and I would even say that they are not needed on any server/workstation unless it is configured as print server (still I would doubt about utility of that service). Quick test: disabling both services, restarting CPSVC.exe and checking if I can launch/reconnect now to the published desktop was successful. One more time it occurred that Citrix has difficulties with HP print drivers – that wasn’t the first time that they caused problems in my farm. That’s why we haven’t added HP Universal Print Drivers to the Replication List in the farm configuration.
The last step was to define new settings in Citrix global GPO:
One more time we finished with happy ending 🙂 And the end moral this story (partly by colleague of mine, I hope he will not sue me for that):
“Never underestimate printing (by my colleague). And beware of HP print drivers – use XEROX :)”