The first line in each entry of the nrfutil device list command output is always the serial number of the found device.
Use this value with the --serial-number flag when you need to target a specific device.
Serial numbers have different formats depending on the device type:
- Development kits and J-Link debug probes — numeric digits (for example,
1090163479or1050263579). - nRF52840 Dongle — 12 characters, digits and letters (for example,
A1234B5678C9). - Nordic Thingy:91 and Nordic Thingy:53 — 20 characters (for example,
THINGY91_C2E0AC7F599orTHINGY53_C2E0AC7F599). - Nordic Thingy:91 X — 21 characters (for example,
THINGY91X_C2E0AC7F599).
When in doubt, run nrfutil device list and copy the serial number from the first line of the device entry.