I have setup the xvfb server on my headless server and when I m running the DISPLAY=:99 firefox I am getting this exception missing RANDR extension
Many of them said to disable some xinerna from the xorg.conf file but this file is not getting created in my case.
So I am searching for how to add the missing RANDR extension.
First off, Xvfb doesn't read configuration from xorg.conf. Xvfb is a variant of the KDrive X servers and like all members of that family gets its configuration from the command line.
It is true that XRandR and Xinerama are mutually exclusive, but in the case of Xvfb there's no Xinerama in the first place. You can enable the XRandR extension by starting Xvfb using at least the following command line options
Xvfb +extension RANDR [further options]
I am seeing this error message when I run Firefox headless through selenium using xvfb. It turns out that the message was a red herring for me. The message is only a warning, not an error. It is not why Firefox was not starting correctly.
The reason that Firefox was not starting for me was that it had been updated to a version that was no longer compatible with the Selenium drivers that I was using. I upgraded the selenium drivers to the latest and Firefox starts up fine again (even with this warning message about RANDR).
New releases of Firefox are often only compatible with one or two versions of Selenium. Occasionally Firefox is released with NO compatible version of Selenium. When that happens, it may take a week or two for a new version of Selenium to get released. Because of this, I now keep a version of Firefox that is known to work with the version of Selenium that I have installed. In addition to the version of Firefox that is kept up to date by my package manager, I have a version installed in /opt/ (eg /opt/firefox31/). The Selenium Java API takes an argument for the location of the Firefox binary to be used. The downside is that older versions of Firefox have known security vulnerabilities and shouldn't be used with untrusted content.
I had the same problem with Firefox 30 + Selenium 2.49 + Ubuntu 15.04.
It worked fine with Ubuntu 14 but after upgrade to 15.04 I got same RANDR warning and problem at starting Firefox using Xfvb.
After adding +extension RANDR it worked again.
$ vim /etc/init/xvfb.conf
#!upstart
description "Xvfb Server as a daemon"
start on filesystem and started networking
stop on shutdown
respawn
env XVFB=/usr/bin/Xvfb
env XVFBARGS=":10 -screen 1 1024x768x24 -ac +extension GLX +extension RANDR +render -noreset"
env PIDFILE=/var/run/xvfb.pid
exec start-stop-daemon --start --quiet --make-pidfile --pidfile $PIDFILE --exec $XVFB -- $XVFBARGS >> /var/log/xvfb.log 2>&1
来源：https://stackoverflow.com/questions/12644001/how-to-add-the-missing-randr-extension