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XenDesktop 7.6 Black Screen issue with VMWare SVGA 3D Driver

12. May 2015

During the last weeks I was facing a strange black screen problem in a XenDesktop 7.6 environment. A rollout for a new division was planned. An image was created and deployed with MCS. One user was chosen to test if everything is working. During the first few days everything was working fine. But after a few days the user always saw a black screen after logging in – nothing more. Interestingly this only happened when he arrived in the morning. Though after successfully logging in it was possible to logout and login again (to another VM) without any problems. When we tried to reproduce it this was nearly impossible – only sometimes the same problem was happening with our test user. But also this only happened at the first login in the morning.

We started to search for solutions and tried the following ones:

First we activated the Legacy graphics mode and assigned it to the affected VMs.
2015-04-02 15_47_18-RDS - DEDAM-SV421 - Royal TS

Then we disabled the Desktop Composition Redirection.
2015-04-02 16_14_41-RDS - DEDAM-SV421 - Royal TS

Still the black screen occurred. So we changed the Receiver Version (a Thin Client with Linux was used) from 12 to 13 – but it was still the same. So we decided to test it with a Windows Client and Receiver 4.2. But as you expect – still the same.

So it was time for a more intensive debugging.

We changed the following registry entries to make sure there is no problem with the MFAPHOOK:

Path: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows
Name: AppInit_DLLs

Path: HKLM\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Windows
Name: AppInit_DLLs

As you can see in the following screenshots the value always contained the full before path.

2015-02-12 14_23_34-dedam-wv300 win_7-x64-Personalabteilung on

2015-02-12 14_24_26-dedam-wv300 win_7-x64-Personalabteilung on

2015-02-12 14_27_10-dedam-wv300 win_7-x64-Personalabteilung on

After:2015-02-12 14_28_13-dedam-wv300 win_7-x64-Personalabteilung on

The next step was to modify some Graphics Drivers Registry settings. We renamed the following keys to .old and restarted the VMs.



2015-05-06 12_40_25-dedam-ctxwv0509 on

After the reboot the keys had been recreated – with different sub keys.
2015-05-06 12_46_11-dedam-ctxwv0509 on

After trying all of these settings I remembered a case where I had the same problem with XenDesktop 5.x – the solution was to remove the VMWare SVGA-Driver. So we now also removed the driver.
2015-05-06 12_52_01-dedam-ctxwv0509 on

After removing the driver the Graphics-Card was shown as “Default-VGA-GraphicsCard” (with a Warning).
2015-05-06 12_54_20-dedam-ctxwv0509 on

And guess what? The black screen was gone. Furthermore we disabled Legacy Graphics Mode and enabled Desktop Composition Redirection – the black screen issue still didn’t happen any longer.

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