This error indicates that you have attempted to execute a command that iPXE does not recognise.

Things to try:

• Ensure you've entered “kernel” before a line if you're executing a kernel.

• Check the spelling of the command.

• Check that the command exists in the list of iPXE commands.

• Check that the command is enabled in your build of iPXE. Some commands are not enabled by default. For example, the vcreate command, which creates a VLAN interface, is available only when the build option VLAN_CMD is defined.