devserver.py returns error when trying to fetch update

When I run the devserver.py file and then, from a cros vm, run update_engine_client --update to fetch the update, devserver.py hits this error. ERROR:root:Failed to read app data from chromiumos_base_image.bin-package-sizes.json ('appid').  I am not sure what it is, but from looking in the nebraska.py file, is it something the vm should send?