When booting with Headless mode enabled on a server, ESXi does not display the installer interface or DCUI
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When booting with Headless mode enabled on a server, ESXi does not display the installer interface or DCUI


Article ID: 323620


Updated On:


VMware vSphere ESXi


The message Relocating modules and starting up the kernel normally indicates that the mboot bootloader has successfully loaded the VMkernel and passed control to it. There can be other causes for an ESXi startup which fails at this point, however.

This article describes a specific failure in which the VMkernel continues to boot successfully but does not display anything on the console.

If the serial logs are blank or do not contain the text described above, then failure is due to a different cause.

  • During installation or boot of an ESXi server, the startup sequence stops in the mboot bootloader and either:
    • Displays the message: Relocating modules and starting up the kernel
    • Displays a blank or black screen.

    In particular, the Direct Console User Interface (DCUI) or Installer (weasel) is not displayed.
  • Serial line logs from a boot attempt show the log messages:

    VMB: ACPIParseFADT:370: Headless mode is set.
    VMB: TermInit:100: VGA not available, headless flag is set in ACPI FADT
    cpu0:nnnnnnn)Keyboard: EarlyInit:187: keyboard disabled, headless flag is set in ACPI FADT
    cpu0:nnnnnnn)PCI: Init:195: VGA not available, headless flag is set in ACPI FADT

    For more information, see Enabling serial-line logging for an ESXi/ESXi host (1003900).
  • After startup, if networking is configured, the ESXi host is still reachable on the network using Ping, SSH, the vSphere Client, and vCenter Server. Virtual machines can be started and managed normally.


VMware vSphere ESXi 6.7
VMware vSphere ESXi 5.5
VMware vSphere ESXi 6.5
VMware vSphere ESXi 7.0.0
VMware vSphere ESXi 6.0


Beginning with ESXi 5.5, the VMkernel supports installation on servers with no video display device, either local (physically attached monitor) or remote (ILO, DRAC, RSA, etc). Servers without video display are called headless servers.

If a server identifies itself as headless, the VMkernel does not initialize the local console terminal and it is expected that all interaction will be done via answer files or remotely via SSH or Serial connections. Servers identify themselves as headless by a flag in the Fixed ACPI Description Table, a set Prior versions of ESXi ignored this flag and always initialized the local console terminal.

Some systems which have a video display device can be configured to report themselves as headless via the configuration, usually in the system BIOS. For these systems, it is usually preferable to use a non-headless configuration.


Enter the system configuration or BIOS and disable Headless Mode.

For additional instructions on entering and configuring the system BIOS, please consult your server vendor's product or mainboard documentation.


If the server hardware platform has a display device, but claims to be headless in the ACPI configuration, and/or the server does not provide a way to configure it in the BIOS, use an advanced VMkernel boot-time configuration option to ignore the ACPI configuration and use the local console anyway.

  1. Press Shift+O during startup of an ESXi installation.
  2. Append the boot option

  3. Press the Enter key to continue boot.
  4. Once installation is completed, set the VMkernel boot-time parameter in persistent configuration using the command:

    esxcfg-advcfg -k TRUE ignoreHeadless