[CentOS] Xwindow: unable to connect to display in CR 6.8

Tue May 17 16:20:00 UTC 2016
Gilbert Sebenste <sebenste at weather.admin.niu.edu>

> On Mon, 16 May 2016, Gilbert Sebenste wrote:
>>  Hello everyone,
>>  I just installed the CentOS 6.8 updates from the CR repository,
>>  and then I rebooted the server. I run some software to make weather
>>  images on a website, and I have run into a problem. When I do it, the
>>  software, as it tries to plot the image, says:
>>  Xwindow: unable to connect to display
>>  It just stopped working when I did the updates. Has anyone else seen this,
>>  or have an idea on what to look for to get this fixed? To plot it, I
>>  use syntax's of
>> machine:  0
>> machine:  1
>> machine:  2
>>  Which lets me plot it using virtual frame buffers (Xvfb). When I do xhost
>>  + servername , it says it has been added to the control list...but it
>>  still doesn't fix the issue. Does anyone know what I may be doing wrong?
> Also, doing an "xhost +" does not help, either, and in /etc/gdm/custom.conf, 
> I have:
> DisallowTCP=false
> Any ideas would be greatly appreciated. Thank you!

I tried reverting to the previous version of x11-Xvfb-server in CentOS 
6.7, and that did not help at all. I am wondering if something is up with 
GDM or the X11 server, but port 6000 isn't even showing up now as active.



Gilbert Sebenste                                                    ********
(My opinions only!)                                                  ******