Customer uninstalled the VDA to upgrade to a later version but now they see a black screen when they try to logon to the console.

The event logs show that LogonUI.exe was crashing.

Copy the file 'C:\Program Files\Citrix\HDX\bin\CUtilDll64.dll' from a working VDA to the affected VDA.

Administrators are now able to log on and complete the uninstall and subsequent upgrade.

Problem Cause

The VDA was incorrectly restarted before the uninstallation completed resulting in a partial uninstall where some files were removed but still configured to be loaded. 

The black screen was caused by LogonUI.exe attempting to call CUtilDll64.dll, which was deleted by the failed uninstall.