> How would I go about getting the 'image_version' and 'radio_version'
> to display within this error message?

Might be cleanest to separate out the building of the string from the
raise. Something like:

msg = ("Upload finished, but the 'Other Settings' "

       "could not be sent because the firmware "

       "version of the image (%s) does not match "
       "that of the radio (%s).")
raise errors.RadioError(msg % (image_version, radio_version))