When an external user launches an application on StroreFront through NetScaler Gateway the following error message is displayed in the web browser:
"Cannot start desktop <name of the desktop resource>"

The Secure Ticket Authority (STA) settings are verified and StoreFront can be accessed internally and the applications can be launched successfully as well.

In Event Viewer > Applications and Service Logs > Citrix Delivery Services, the following error messages appear:
"Source - Citrix Store Service
Message - All the configured Secure Ticket Authorities failed to respond to this XML transaction.
Message - An SSL connection could not be established. None of the SSL cipher suites offered ..... were accepted by the server. The specified Secure Ticket Authority could not be contacted and has been temporarily removed from the list of services."

To resolve this issue install the revised version of KB2992611.

To workaround this issue, go to the STA field for NetScaler Gateway and change https to http.

Problem Cause

This is a known issue caused by Windows 2012 Update 1.

Citrix Discussions - Unable to Start Desktop

Citrix Discussions - 2012R2 Update breaks HTTPS between StoreFront 2 and XD 7.1 DDC