This error usually indicates an unrecognised image format or, less commonly, a corrupted image.

Things to try:

• Check that your build of iPXE supports the type of image you are trying to boot. You can see the list of supported image types in the iPXE start-up banner; for example:

      iPXE 1.0.0+ -- Open Source Network Boot Firmware -- http://ipxe.org
      Features: HTTP iSCSI DNS TFTP AoE VLAN bzImage COMBOOT ELF MBOOT PXE PXEXT

  shows that bzImage, COMBOOT, ELF, Multiboot, and PXE images are supported in this build of iPXE.

• Check that the image you are trying to boot has not been corrupted in any way.

• If you are trying to boot an iPXE script, check that the “#!ipxe” signature is present at the beginning of the script.

• If you are trying to boot an iPXE script, and you have edited the script on a Windows machine, check that the script was saved using ASCII (or UTF-8) rather than UTF-16 encoding.