This error indicates that you have attempted to download a file that is too big to fit into the available RAM.
Things to try:
If you are downloading multiple images, check that you have freed any images that you no longer need. You can view the currently downloaded images using the
imgstat
command, and free any unwanted images using the
imgfree
command.
If you are downloading an entire disk or
ISO image (e.g. for booting with
MEMDISK), then consider using a
SAN boot instead.