A user is able to start multiple instances of a published application though the Allow only one instance of application for each user option enabled in the Published Application Properties.

This might cause multiple disconnected sessions of a limited published application which introduces additional issues when the users are attempting to reconnect to those sessions.

Some users are unable to successfully start or reconnect to a published application. They might receive the following message:

“You already have an instance of this application open and are not allowed to run more than one instance. Please contact your System Administrator.”

Caution! Using Registry Editor incorrectly can cause serious problems that might require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.

Caution! Refer to the Disclaimer at the end of this article before using Registry Editor.

The SucConnTimeout parameter was added to the ICA Client in version 8.x to help prevent users from starting applications quickly.

The parameter can be placed with a default value of 20 seconds in the WFClient section of the appsrv.ini file on a client or the default.ica file for the Web Interface site. Some applications take more time to start up, so set it to 40 or 60 seconds for a higher value.

Example of parameter setting in the APPSRV.INI or DEFAULT.ICA file:
[WFClient]
Version=2
SucConnTimeout=40

In addition, the registry key can be updated on the clients desktop to extend this time out value:
HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\ICA Client\Engine\Configuration\Advanced\Modules\WFClient\ SucConnTimeout = <string value>
Note: <string value> must be set to 20 or more.
When Multi-site aggregation is configured on Storefront then above registry entry will no longer work.

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Problem Cause

Users rapidly clicking published application icons can initiate multiple sessions prior to the application instance counter getting updated.

User is able to start multiple instances of a published application though the Allow only one instance of application for each user option is enabled in the published Application Properties.

CTX114379 - Session Sharing Does Not Occur if You Click on Multiple Applications at the Same Time

CTX159159 - Session Sharing Explained with Troubleshooting Steps