Published desktops may

• Launch to a grey screen
• Fail to launch 

Published seamless applications may

• Fail to launch
• Launch, run through loading progress window, then disappear
• Launch to non seamless session

VDA event logs:

• Error 1002 - The Citrix Universal DLL Injection Driver has detected an integrity error during initialization. The Citrix Universal DLL injection Driver has been disabled.

Citrix features are implemented by loading a number of DLL modules into the address space of each application and hooking certain API calls. Citrix loads the DLLs specified by keys under the following registry key --

For Windows 32-bit version
Key: HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\CtxHook

For Windows 64-bit version
Key: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Citrix\CtxHook

To resolve this issue, disable the component/policy that is modifying the above registry path.

Note: Depending on the problem created, running VDACleanup utility and reinstalling the VDA may be also required.

 

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Problem Cause

Xendesktop/XenApp VDA 7.9 and newer utilises Kernel APC Hooking as a replacement of AppInit_DLLs
The KAPC Hooking DLL Injection Driver (CtxUvi) verifies that the hook DLLs configuration in the registry is not changed at runtime (i.e. HKLM\SOFTWARE\Citrix\CtxHook\AppInit_DLLs\<hook name>).
If a change to the configuration is detected the CtxUvi driver disables itself until the next reboot.
 

Troubleshooting Gray or Black Screen

VDA Cleanup Utility

Citrix API Hooks (mfaphook.dll) Explained and Enumerated

How to verify if Citrix hooks are loaded in a process