# 4.9.0 nightly build cannot be run on a VNC server due to Qt5-GLX problem

**URL:** <https://discourse.slicer.org/t/4-9-0-nightly-build-cannot-be-run-on-a-vnc-server-due-to-qt5-glx-problem/3185>\
**Category:** Support\
**Tags:** bug, nightlybuild\
**Created:** [June 14, 2018, 8:02pm UTC](https://discourse.slicer.org/t/4-9-0-nightly-build-cannot-be-run-on-a-vnc-server-due-to-qt5-glx-problem/3185 "2018-06-14T20:02:29Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ferhue](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ferhue/32/82557_2.png) [@ferhue](https://discourse.slicer.org/u/ferhue)\
**Post date:** [June 14, 2018, 8:02pm UTC](https://discourse.slicer.org/t/4-9-0-nightly-build-cannot-be-run-on-a-vnc-server-due-to-qt5-glx-problem/3185/1 "2018-06-14T20:02:29Z")

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I am using a VNCviewer to connect to a remote Ubuntu 16 server, where I have installed 3DSlicer.

I downloaded the stable release and run it without problems as:

> user@pgdev:~$ /opt/Slicer-4.8.1-linux-amd64/Slicer  
> Number of registered modules: 161  
> Number of instantiated modules: 161  
> Number of loaded modules: 161  
> Switch to module: “Welcome”  
> Loaded volume from file: /home/user/.config/NA-MIC/Extensions-26813/SlicerVMTK/lib/Slicer-4.8/qt-scripted-modules/Resources/Vesselness.png. Dimensions: 65x50x1. Number of components: 3. Pixel type: unsigned char.

However, with the nightly build 4.9.0, it does not work any more, thus I report the problem.

> user@pgdev:~$ /opt/Slicer-4.9.0-2018-06-11-linux-amd64/Slicer  
> QStandardPaths: XDG\_RUNTIME\_DIR not set, defaulting to ‘/tmp/runtime-user’  
> QXcbConnection: Failed to initialize XRandr  
> Qt: XKEYBOARD extension not present on the X server.  
> Could not initialize GLX  
> error: [/opt/Slicer-4.9.0-2018-06-11-linux-amd64/bin/SlicerApp-real] exit abnormally - Report the problem.

Seems to be a Qt5 issue. I tried the solutions posted here, but to no avail: [No keyboard responding for Spyder when started through VNC · Issue #3713 · spyder-ide/spyder · GitHub](https://github.com/spyder-ide/spyder/issues/3713)

Here my system info:

> user@pgdev:~$ uname -a  
> Linux pgdev 4.4.0-127-generic #153-Ubuntu SMP Sat May 19 10:58:46 UTC 2018 x86\_64 x86\_64 x86\_64 GNU/Linux  
> user@pgdev:~$ cat /etc/os-release  
> NAME=“Ubuntu”  
> VERSION=“16.04.4 LTS (Xenial Xerus)”  
> ID=ubuntu  
> ID\_LIKE=debian  
> PRETTY\_NAME=“Ubuntu 16.04.4 LTS”  
> VERSION\_ID=“16.04”  
> HOME\_URL=“[http://www.ubuntu.com/](http://www.ubuntu.com/)”  
> SUPPORT\_URL=“[http://help.ubuntu.com/](http://help.ubuntu.com/)”  
> BUG\_REPORT\_URL=“[Bugs : Ubuntu](http://bugs.launchpad.net/ubuntu/)”  
> VERSION\_CODENAME=xenial  
> UBUNTU\_CODENAME=xenial

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**Author:** ![ihnorton](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ihnorton/32/9_2.png) [@ihnorton](https://discourse.slicer.org/u/ihnorton)\
**Post date:** [June 14, 2018, 9:49pm UTC](https://discourse.slicer.org/t/4-9-0-nightly-build-cannot-be-run-on-a-vnc-server-due-to-qt5-glx-problem/3185/2 "2018-06-14T21:49:57Z")

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You could try `export LIBGL_ALWAYS_INDIRECT=1`, in the shell, before launching Slicer.

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**Author:** ![ferhue](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ferhue/32/82557_2.png) [@ferhue](https://discourse.slicer.org/u/ferhue)\
**Post date:** [June 14, 2018, 9:58pm UTC](https://discourse.slicer.org/t/4-9-0-nightly-build-cannot-be-run-on-a-vnc-server-due-to-qt5-glx-problem/3185/3 "2018-06-14T21:58:35Z")

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Thanks, but does not work, I get the exact same error message.

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [June 16, 2018, 2:12am UTC](https://discourse.slicer.org/t/4-9-0-nightly-build-cannot-be-run-on-a-vnc-server-due-to-qt5-glx-problem/3185/4 "2018-06-16T02:12:58Z")

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As an alternative solution, you can use virtualgl on your vncserver. You will need to execute the slicer through vglrun command.

[https://virtualgl.org/vgldoc/2\_1\_1/](https://virtualgl.org/vgldoc/2_1_1/)

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**Author:** ![fedorov](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/fedorov/32/14_2.png) [@fedorov](https://discourse.slicer.org/u/fedorov)\
**Post date:** [March 19, 2020, 8:14pm UTC](https://discourse.slicer.org/t/4-9-0-nightly-build-cannot-be-run-on-a-vnc-server-due-to-qt5-glx-problem/3185/5 "2020-03-19T20:14:53Z")

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@ferhue another user reported this problem. Can you let us know what worked for you? Were you able to figure this out?

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**Author:** ![ferhue](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ferhue/32/82557_2.png) [@ferhue](https://discourse.slicer.org/u/ferhue)\
**Post date:** [March 19, 2020, 9:51pm UTC](https://discourse.slicer.org/t/4-9-0-nightly-build-cannot-be-run-on-a-vnc-server-due-to-qt5-glx-problem/3185/6 "2020-03-19T21:51:36Z")

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I never solved it, I just used it with grdesktop instead of VNC viewer.

I just tried again with Ubuntu 18 and Slicer 4.10.1 and it does not crash, however I get a black screen.

Below the errors printed in terminal:

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/b/c/bcad818cdb5093ff2ee3f16a2f0ea3aa2ed81018.png)