"The Citrix server has reached its concurrent application limit for this application" affecting one user

Hi Guys,

I have an interesting issue where one user gets the "The Citrix server has reached its concurrent application...." when trying to run an application. The app published is a desktop and the screen goes black as if its going to start but then presents the error popup.

The environment I manage is running a 6 x server Citrix setup with the following:
1x - CAG
1x - Web Interface
1x - Data Collector
3x - XenApp Servers

We are running XenApp 6.5.

I have recreated a new profile (newuser1) for the user to get them going and this new profile is working OK.

I would like to however get to the bottom of it so I can prevent it from happening in future.

I have looked in the Event Viewer for the Web Interface and the Data Collector but can't find anything relating to this profile lets call it user1.

I tested profile "user1" on my own machine and could replicate the problem. I tested my own profile on the "user1"'s PC and it works OK so this leads me to believe its not an individual PC that's at fault.

When the "user1" signs on and the error message appears, I don't see "user1" even appear at all under the "Connected Users" for the application under the "Citrix App Center".

This is only affecting one user, and I have about 35 other users that are working OK.

Can anyone lead me in the right direction?

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Ayman BakrSenior ConsultantCommented:
Most probably you have set limits on the number of instances that a user can start for the published desktop.

This message clearly indicates that the user facing the issue has an instance already opened; but it doesn't show in the Citrix console because it is in the down state.

If you check the RDS management console you will be able to see that the user already has a session and perhaps one or more processes are already hanging for him (maybe TSTheme.exe). You need to kill these processes to force the logoff for the user.
vasbozAuthor Commented:
Hi Mutawadi,

Yes there are limits set, this is "Allow only one instance of application for each user" which is OK and what we prefer.

Looking under the Citrix App Center however I cannot see any disconnected, or connected sessions under the Session State column relating to "User1".

Looking under the RDS Manager within "Sessions" I can also not locate "User1".

Also, looking in the Task Manager for each of the servers I can't see any rogue processes hung belonging to "User1".
Ayman BakrSenior ConsultantCommented:
What about if the user 'user1' starts any other application - say publish notepad. Does it launch?

If that launches, but the intended application doesn't; then there is no doubt that the process is hanging and somehow is hidden that it is not apparent in any console.

I have faced several users who have one of their applications' process hanging on several servers (despite the fact that we have set the limit to one instance because they click several times on the icon before the application start on any one of the servers). Even after terminating the application and logging the user off from all the servers from the AppCenter the application refuses to start - at which point I discovered that it is hanging on their Citrix plugin. The only way to stop it at that moment was to launch task manager on the client's PC and end the processes belonging to-  the Citrix plugin.

How often do you restart your servers? It looks like you don't do that practice. It is best practice to start doing it - at least such cases would be almost eliminated since any hanging process would die with the restart.

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vasbozAuthor Commented:
Hi Mutawadi,

Publishing notepad works -OK. I re-tested with the Smeg Desktop application and it is still appearing as though it launches, with the full screen black (seamless experience) and then shows the concurrent connection server error...

I have also experienced similar to what you've mentioned about users clicking on the icon several times.

I have scheduled in a restart for our servers outside of business hours which I'll perform in 5 hours time.

I do restart the servers but I only do that once every two weeks.

I will report back after that whether it is working.

My only issue with "restarting" the server, if this does fix the issue, is that it doesn't explain what caused the issue in order to mitigate this in future...

Also in response to the plugin being corrupt comment in your last post, I have tried "User1"'s profile from my machine with the same result, but using a different profile it works fine, eliminating the thought that its the plug-in that has crashed.
Ayman BakrSenior ConsultantCommented:
I agree with you on all what you mentioned.

However, since notepad works fine; it is very clear that the issue is having the process of the application for that user hanging somewhere in the background - but the real issue is where to locate it?

I will be awaiting to see the results after restarting the servers.
vasbozAuthor Commented:
Hi Mutawadi,

Following the restart, I can now confirm that the user account "User1" which had the fault is now working A-OK.

Seems the restart did it good.

Ayman BakrSenior ConsultantCommented:
Happy to help ;)
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