1. Check the current running Kernel Version 2. List the Kernel Entries as per GRUB2 file: 3. Let us modify the Kernel Version to "CentOS Linux (5.8.5-1.el7.elrepo.x86_64) 7 (Core)" which is at line number 2 but denoted as entry 1. 4. Changes to /etc/default/grub require rebuilding the grub.cfg file as follows: Reboot the Server and it will boot with Kernel Version 5.8.5-1.el7.elrepo.x86_64.