> I updated to Centos 6.8. > Every thing is working, except Xorg does not startup. > When I look at top, it seems that Xorg keeps trying but not > succeeding to start. > Any idea what the problem might be? I had the same problem going to 6.8. In my case the problem stemmed from the fact that my machine has a MACH64 video card. The updated Xorg has a reference xf86LinearVidMem. I opened bug 1422622 at bugzilla.redhat.com. This was on 2/15/2017. So far the bug is just sitting there. My work around was to disable the main repo's in /etc/yum.repos.d and enable 6.7 in the vault repo. Did a distribution synchronization. Here are the notes from what worked: (may be line wrapping issues in what follows) Went back to the x64 version and figured out how to roll back to 6.7: mount -t nfs phxbkup2:/iso/centos6.7x64 /media/CentOS # This one failed with dependency issues yum --disablerepo=\* --enablerepo=c6-media --releasever=6.7 distribution-synchronization # Erased the problem packages yum --disablerepo=\* --enablerepo=c6-media --releasever=6.7 erase python-libipa_hbac-1.13.3-22.el6_8.4.x86_64 mesa-libxatracker-11.0.7-4.el6.x86_64 xorg-x11-drivers-7.3-13.4.el6.x86_64 mesa-libxatracker-11.0.7-4.el6.x86_64 yum --disablerepo=\* --enablerepo=c6-media --releasever=6.7 erase xcb-util xcb-util-renderutil # Now it worked yum --disablerepo=\* --enablerepo=c6-media --releasever=6.7 distribution-synchronization # put pack the drivers yum --disablerepo=\* --enablerepo=c6-media --releasever=6.7 install xorg-x11-drivers yum --disablerepo=\* --enablerepo=c6-media --releasever=6.7 install python-libipa_hbac mesa-libxatracker mesa-libxatracker # These not available on the media and not reinstalled. python-libipa_hbac mesa-libxatracker mesa-libxatracker # Now it worked.