Troubleshooting an ESX host that does not boot
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Troubleshooting an ESX host that does not boot


Article ID: 340492


Updated On:


VMware vSphere ESXi


  • When an ESX host boots and gets to the login screen, you see a line of errors similar to:

    Error: Signature mismatch between VmkCtl ( DateTime) and VMKernel ( _Unknown_)
    Can't access TTY: Job control turned off

  • The line or error changes every time it reboots. It also displays the error:

    Util : 815 : Status 0xbad0001 trying to get a valid VMKernel MAC address. Various vmkernel subsystems will provide lower quality of service

  • If you restart the ESX host, you see the error:

    Grub error 15: File not found


VMware ESX Server 3.0.x
VMware ESX 4.0.x
VMware ESX Server 3.5.x
VMware ESX 4.1.x


This issue occurs if the esx.conf file in the initial ramdisk (INITRD) is corrupted or contains invalid configuration. Use the esxcfg-boot command-line utility on the ESX host to create a new initial ramdisk based on the configuration file at /etc/vmware/esx.conf.

To create a new intial ramdisk:

  1. Select the Troubleshooting or Service Console Only boot option when the GRUB bootloader appears.
  2. Log into the terminal as root.
  3. Run these commands:

    • ESX 3.x:

      esxcfg-boot -p
      esxcfg-boot -b
      esxcfg-boot -r

    • ESX 4.x:

      esxcfg-boot -b

    • Reboot the ESX host using the reboot command.


    • Previous ESX 3.0 configuration files can be recovered from /var/log/oldconf. Other ESX hosts with identical configurations can be inspected to compare settings.

    Additional Information:

    If you see error 15 file not found error its an issue with possible corruption of the GRUB boot loader which is used in ESX 3.x and ESX 4.x hosts.
    To fix the issue with GRUB corruption use the command:

    # esxcfg-boot -b

    See Also: