Xvfb Failed Start Error

I was getting this error "xvfb-run: error: Xvfb failed to start" on Ubuntu 14.04, where previously my script had run without problems on Ubuntu 12.04.

My scripts were running calling xvfb-run multiple times, but I was seeing fails due to the error "Server is already active for display 99"

It seemed that the Xvfb wasn't ending when the xvfb-run command returned.

My solution was to use "xvfb-run -a [mycommand]" so xvfb uses another display if 99 is in use.

Had the same issue, solved it by running this instead:

xvfb-run --auto-servernum --server-num=1 [your script]

--auto-servernum : Try to get a free server number, starting at 99, or the argument to --server-num

Run xvfb-run -e /dev/stdout [mycommand] as @wumpus suggested.

I received the server lock message:

Fatal server error:
Could not create server lock file: /tmp/.X99-lock

xvfb-run: 

error: Xvfb failed to start

Using sudo resolved the issue for me:

sudo xvfb-run -e /dev/stdout [mycommand]

Found the problem There is hanging process in system with name

Xvfb

I killed it and work fine. I newer found it earlier beacuse I used to try to find process with 'xvfb' name

I came across this error when running a bash script on Mac OS. Opening XQuartz before running the script solved my problem.