I did usual upgrade and upon reboot I noticed an error and X crashed .
================ WARNING WARNING WARNING WARNING ================ This server has a video driver ABI version of 7.0 that this driver does not officially support. Please check http://www.nvidia.com/ for driver updates or downgrade to an X server with a supported driver ABI. ================================================================= (EE) NVIDIA: Use the -ignoreABI option to override this check. (II) UnloadModule: "nvidia" (II) Unloading /usr/lib64/xorg/modules/drivers/nvidia_drv.so (EE) Failed to load module "nvidia" (module requirement mismatch, 0) (EE) No drivers available.
Upon google search I found a simple fix by adding the following section to /etc/X11/xorg.conf
Section "ServerFlags" Option "IgnoreABI" "True" EndSection
Upon reboot things were back to normal, X worked fine and I could login back to KDE desktop through KDM without any issues .