My customer ran a yum update on their virtual server. After they rebooted it, it did not come back up.


All OnApp versions


To boot a virtual server, the kernel should be rolled back to the previous version:

  • Boot the virtual server in recovery mode via the OnApp UI.
  • Go the virtual server command prompt, log in as root. The password should be recovery:
  • Once logged in, run:

    fdisk -l
  • Find the disk for the virtual server (for example, /dev/sdb1, 20 GB). 
  • Mount the disk:

    mount /dev/sdb1 /mnt 
  • Once the disk is mounted successfully, edit the bootloader file:

    vi /mnt/boot/grub/grub.conf 
  • If the default one is set to 1, try to change it to 0 and boot. Otherwise, choose the number of the kernel you want to boot.  

    Please note that 0 is the top kernel in the list.

  • Unmount the disk:

    umount /mnt
  • Disconnect from the command prompt and shut down the virtual server from the OnApp UI.
  • Boot it up.


Usually it happens if the updated kernel is not a XEN kernel. Therefore, the virtual server is unable to boot under XEN.