Citrix XenApp and Windows RDS Licensing Event ID 4105

Scott Fowler
Scott Fowler used Ask the Experts™
We have two Citrix XenApp servers – “CTX1” and “CTX2” respectively. On CTX1 we’re seeing Event ID 4105 in the Windows System log. Apparently this error is related to Remote Desktop Services licensing. After digging a little deeper I found that CTX1 is configured as our RDS licensing server. This seems less than ideal, because we have another server, “CTXWeb”, which is handling our Citrix Licensing. It seems like RDS licensing should also be on CTXWeb. So a couple of questions for the experts:

1) Could Event ID 4105 be negatively impacting our Citrix environment? (We’ve had issues with disconnects and sessions freezing the past few months.)

2) Would it be a better scenario if we moved RDS licensing onto CTXWeb where the Citrix licensing also resides? Or should they be on separate servers?

We’ve been trying to get our VPN experience to be as smooth as possible, so any “best practices” you can suggest would be appreciated.
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Citrix Consultant
Depending on the environment, I install the role on the same server that hosts the Citrix Licensing Service, or on an AD Domain Controller.  If you install the role on a DC, then you won't need to follow the steps in the article.  If you put it anywhere else, you will need to make sure you follow the steps in the article you posted.  I certainly would not install licensing on a Citrix worker server in any case.  CTXWeb sounds like it would be fine.  There's no tie between Citrix Licensing and RDS Licensing, but they won't conflict with each other.  I like the DC option personally since it will be a more permanent solution in the event of Citrix upgrades in the future.
great explained by Brian.
the typical error with RDS licensing problems within a Citrix environment occurs not within a working session.
Mostly you see errors like "protocol or driver error" while trying to establish the session.


Per Brian's input we went ahead and installed RDS licensing on the same server as Citrix licensing. After following the instructions in the KB article the 4105 errors ceased.

Thanks for the help!
Brian CTXSupportCitrix Consultant

Sorry, I glossed over this part of your question:

"1) Could Event ID 4105 be negatively impacting our Citrix environment? (We’ve had issues with disconnects and sessions freezing the past few months."

Licensing wouldn't affect system performance in that way.  It would only prevent a session from being established if a license server couldn't be contacted, and the server is beyond it's 120 day grace period from the time the RDS role was installed.

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