Ah, good spot. Thanks for reporting this. It seems the firmware.hex was accidentally omitted for the last release of emontx-3phase. This has now been fixed
Please try again now. I’ve just checked and now emonupload is successfully downloading the 3phase firmware. Apologies for the hassle.
The hex file can also be downloaded from: Release V1.4.0: Support 3 or 4-wire systems · openenergymonitor/emontx-3phase · GitHub
@Robert.Wall apologies, your reply was totally valid. No need to delete. Please don’t take my alternative suggestion personally.