Problem Definition: 

Attempting to connect to a Citrix desktop fails with status "Unknown client error 0" or "Unknown client error 1110". The client is using Citrix Receiver 4.9.x for Windows, and the Citrix desktop is using VDA 7.15 LTSR Cumulative Update 2.

Cause: The root cause of the connection failure is unknown. However, it can be remediated by workarounds described below.

Resolution: 

1.) Upgrade the Citrix desktop's VDA to 7.15 CU3. This can be done either manually, or through the DesktopConfig utility. 

For further information and procedure, see: Upgrade a Citrix Server Configuration to the Latest CloudConnect Baseline). 

As CloudConnect recommends the use of Citrix Receiver 4.9.9 LTSR, this is the preferred solution.  

- OR -

2.) Install and connect using the Workspace App as opposed to Receiver 4.9. To download the latest stable release, see: Workspace app for Windows Long Term Service Release

Additional Information:

Connectivity through the HTML client is unaffected by this issue, and the HTML client can be used as a quick workaround to connect to the Citrix desktop until one of the above resolutions has been employed. 

To learn how to connect through the HTML client, see: Accessing a Citrix Virtual Desktop through the HTML Client

Applies to:

Citrix Apps and Desktops

Citrix Receiver for Windows