DJI Fly shows a registration number format error when the number you typed doesn't match the format your aviation authority uses. The usual causes: entering the drone's serial number, leaving off the three secret characters at the end, or (in the UK) entering your Operator ID instead of your Remote ID number. Enter the complete number exactly as your authority gave it, with matching upper and lower case, and the error goes away.
Where this number goes
In the EU and the UK, class-marked drones broadcast your operator registration number through Remote ID. DJI Fly asks you to upload it. On the Mavic 3 Pro, for example, DJI's manual puts it under DJI Fly > Safety > UAS Remote Identification. Other DJI Fly drones use the same section.
DJI Fly checks the number before accepting it, using a checksum built into the format. That's why a single wrong character triggers the error.
What the number should look like
Both the EU and UK use the same structure. The UK Civil Aviation Authority spells it out:
| Part | Length | Characters |
|---|---|---|
| Country code | 3 | Upper case (for example GBR, FIN, NOR) |
| Public part | 12 | Lower case letters and numbers |
| Checksum | 1 | A number or lower case letter |
| Private key | 3 | Lower case letters and numbers |
EASA's example of an EU number is written as 16 characters, a hyphen, then 3 characters: the country code, public part and checksum, then the secret part.
Fixes, in order
- Don't use the drone's serial number. DJI serial numbers for Remote ID start with 1581F and run 20 characters. Drone pilots on forums report that entering one returns this exact error. The field wants your operator number.
- Include the last three characters. The secret part isn't printed on your drone label, but DJI Fly needs it to validate the number. The UK CAA says your drone will prompt you to enter the Remote ID number "including the private key" and won't accept an invalid one.
- UK flyers: use the Remote ID number, not the Operator ID. The CAA says the two are "similar" but "not exactly the same." Find your Remote ID number in the My registration area of your CAA account.
- Match the case exactly. The country code is upper case. The rest is lower case. The CAA notes the number is case sensitive.
- Copy and paste if you can. It avoids mixing up 0 and o, or 1 and l.
- Update DJI Fly and the drone firmware, then try again if a correct number still fails.
Keep the secret part private
The three secret characters work like a password. The CAA says never to write them on your drone or share them, and to remove your Remote ID number from the drone if you sell it or lend it out. Only the public part goes on your drone label.
In the US?
The FAA uses a different system. US Remote ID broadcasts the drone's serial number, and you add that serial to your FAA registration, not to DJI Fly. If you're stuck there, see FAA DroneZone not working or which DJI drones have Remote ID.
Flying abroad? Our guides to flying in Europe as a US tourist and UK drone laws cover registration. Need a drone that's easy to travel with? Browse the Mini series.
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