tl;dr⌗

If you deploy published applications using Omnissa App Volumes and Omnissa Horizon 2603 or 2606, users may encounter an error message when launching the application. This is a known bug with Horizon 2603 and Horizon 2606. A hot patch connection server build is available from Omnissa Support to resolve the issue.

The Problem⌗

After upgrading 2 of our Omnissa Horizon pods to version 2603, users reported error messages when attemping to launch published applications delivered through App Volumes. Users would see the error message: ‘Loading Failed: This application is currently not available. Please try connecting to this application again later, or contact your system administrator.’

In the connection server debug logs, we would see errors like this:

2026-08-27T13:38:49.786-04:00 DEBUG (1860-13DC) [LinkedModeDesktopsHandler] LMV: Unsuccessful launch of CN=APPLICATION_NAME,OU=Applications,DC=vdi,>DC=vmware,DC=int for user USERNAME: Cannot invoke “String.startsWith(String)” because “” is null

2026-08-27T13:38:49.786-04:00 INFO (1860-13DC) [AbstractSessionLaunchContext] DOMAIN\username, Application=APPLICATION_NAME: Session request failed.       (null) [DOMAIN\username, Application=APPLICATION_NAME] (5ms): Application launch failed, exception was: Cannot invoke “String.startsWith(String)” because “” is null

The issue is caused by a bug querying user GUIDs. Horizon is attempting to pull the user GUID and is only finding a null value.

The Solution⌗

As a temporary workaround for this issue, you can do the following on your connection servers:

1. Login to the connection server
2. Launch an elevated command prompt
3. Change directory to C:\Program Files\Omnissa\Horizon\Server\tools\bin
4. Run vdmadmin.exe -F
5. Do this on all connection servers in each pod

See the documentation for this command here.

The permanent fix will be a dot release for Horizon 2603 and 2606. We were provided Horizon 2603 connection server build 32686627688 which has resolved the issue for us prior to the dot release.