# XVFB Headless Node

**URL:** <https://discourse.psychopy.org/t/xvfb-headless-node/9372>\
**Category:** Coding\
**Created:** [October 11, 2019, 3:56pm UTC](https://discourse.psychopy.org/t/xvfb-headless-node/9372 "2019-10-11T15:56:32Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Paulo\_Baptista](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.psychopy.org/paulo_baptista/32/5927_2.png) [@Paulo\_Baptista](https://discourse.psychopy.org/u/Paulo_Baptista)\
**Post date:** [October 11, 2019, 3:56pm UTC](https://discourse.psychopy.org/t/xvfb-headless-node/9372/1 "2019-10-11T15:56:32Z")

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Hello All! 🙂

I’m a SYSADMIN at Brown Unviersity trying to help a researcher run some code.

As a test we want to run this code [https://www.programmingvisualillusionsforeveryone.online/Lilac.py](https://www.programmingvisualillusionsforeveryone.online/Lilac.py)

On Ubuntu 16.04, Anaconda, Python 3.6, PsychoPy 3.2.3

xvfb-run -s “-screen 0 1400x900x24 -ac +extension GLX +render -noreset” python g.py  
pygame 1.9.6  
Hello from the pygame community. [https://www.pygame.org/contribute.html](https://www.pygame.org/contribute.html)  
Xlib: extension “XFree86-VidModeExtension” missing on display “:99”.  
Traceback (most recent call last):  
File “g.py”, line 4, in   
myWin = visual.Window(color=[0,0,0], units=‘pix’, size=[1000,1000], allowGUI=False, fullscr=False, gammaErrorPolicy=‘ignore’)#creates a window  
File “/home/x/.conda/envs/psypy3/lib/python3.6/site-packages/psychopy/visual/window.py”, line 416, in **init**  
self.backend = backends.getBackend(win=self, \*args, \*\*kwargs)  
File “/home/x/.conda/envs/psypy3/lib/python3.6/site-packages/psychopy/visual/backends/ **init**.py”, line 32, in getBackend  
return Backend(win, \*args, \*\*kwargs)  
File “/home/x/.conda/envs/psypy3/lib/python3.6/site-packages/psychopy/visual/backends/pygletbackend.py”, line 239, in **init**  
self.\_origGammaRamp = self.getGammaRamp()  
File “/home/x/.conda/envs/psypy3/lib/python3.6/site-packages/psychopy/visual/backends/pygletbackend.py”, line 347, in getGammaRamp  
self.screenID, self.xDisplay, gammaErrorPolicy=self.\_gammaErrorPolicy  
File “/home/x/.conda/envs/psypy3/lib/python3.6/site-packages/psychopy/visual/backends/gamma.py”, line 149, in getGammaRamp  
rampSize = getGammaRampSize(screenID, xDisplay=xDisplay)  
File “/home/x/.conda/envs/psypy3/lib/python3.6/site-packages/psychopy/visual/backends/gamma.py”, line 321, in getGammaRampSize  
raise OSError(raise\_msg.format(func=func))  
OSError: The hardware look-up table (XF86VidModeGetGammaRampSize) was unable to be used. If you would like to proceed without look-up table (gamma) changes, you can set the `Window` parameter `gammaErrorPolicy` to `"warn"` or `"ignore"`.  
3.2585 WARNING Monitor specification not found. Creating a temporary one…  
Exception ignored in: \<bound method Window. **del** of \<psychopy.visual.window.Window object at 0x7f4f558e8048\>\>  
Traceback (most recent call last):  
File “/home/x/.conda/envs/psypy3/lib/python3.6/site-packages/psychopy/visual/window.py”, line 529, in **del**  
self.close()  
File “/home/x/.conda/envs/psypy3/lib/python3.6/site-packages/psychopy/visual/window.py”, line 1517, in close  
self.backend.close() # moved here, dereferencing the window prevents  
AttributeError: ‘NoneType’ object has no attribute ‘close’

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<div class="post-metadata">

**Author:** ![Leon\_Shams-Schaal](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.psychopy.org/leon_shams-schaal/32/8875_2.png) [@Leon\_Shams-Schaal](https://discourse.psychopy.org/u/Leon_Shams-Schaal)\
**Post date:** [June 6, 2020, 6:06am UTC](https://discourse.psychopy.org/t/xvfb-headless-node/9372/2 "2020-06-06T06:06:59Z")

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Change your winType to “glfw” and install this modified version of psychopy which will allow you to run it headless: [https://github.com/mfiless/headless-psychopy](https://github.com/mfiless/headless-psychopy)