This error indicates that the file was not found on the TFTP server.

Things to try:

If your TFTP request is constructed using a TFTP URI, then your TFTP server may need you to add an additional slash (/) character between the server address and the filename. For example:

# Fetch "images/pxeboot.nbp" from TFTP server 192.168.0.1
chain tftp://192.168.0.1/images/pxeboot.nbp

# Fetch "/images/pxeboot.nbp" from TFTP server 192.168.0.1
chain tftp://192.168.0.1//images/pxeboot.nbp