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I am trying to start firefox headless. The following is the beginning of the shell script that starts it:

Xvfb :99 >/dev/null 2>&1 &
sleep 3
firefox --display=:99 >/dev/null 2>&1 &

When this script is run, the following error occurs:

Xlib:  extension "RANDR" missing on display ":99".

I have tried starting Xvfb with the following, but it does not prevent the error:

Xvfb -extension RANDR :99 >/dev/null 2>&1 &


Xvfb +extension RANDR :99 >/dev/null 2>&1 &

Is there a better way to enable XRandR in Xvfb so that firefox is able to see the extension?

Alternatively, is there a way to disable XRandR in firefox?

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