RE: BLE pairing authentication fail after migrating to ncs3.0.2

ziv123 — Sun, 11 Jan 2026 08:01:55 GMT

seems like it is related to this config "CONFIG_BT_SMP_SC_PAIR_ONLY"

which in ncs2.9.2 is not set but in ncs3.0.2 is by default =y .. which means the device expects the gateway to communicate in secure pairing only, and there is no tolerance for gateways which practice legacy pairing (here is the explanation about the diff between the two - https://academy.nordicsemi.com/courses/bluetooth-low-energy-fundamentals/lessons/lesson-5-bluetooth-le-security-fundamentals/topic/legacy-pairing-vs-le-secure-connections/ )

this is mentioned in zephyr 4.1 migration guide https://docs.zephyrproject.org/latest/releases/migration-guide-4.1.html#bluetooth-host:~:text=set%20to%200.-,LE%20legacy%20pairing,-is%20no%20longer

(... i wonder why we must go over migration guides of 4.0, 4.1 and ncs instead of just the ncs for that but that's just me)

changing the config to =y solved the issue and all gateways can connect and pair with the devices now

best regards

Ziv

RE: BLE pairing authentication fail after migrating to ncs3.0.2

Susheel Nuguru — Thu, 08 Jan 2026 11:27:33 GMT

Hi Ziv,

The migration notes for NCSv3.0.0 seems to have stated

 The :kconfig:option:`CONFIG_BT_SMP_SC_PAIR_ONLY` Kconfig option is enabled by default in Zephyr.

If you want the same behavior as before, then maybe you can try setting CONFIG_BT_SMP_SC_PAIR_ONLY=n in your prj.conf to override this new default and see if you get the behavior similar to what you saw with NCSv2.9.0. Test and let me know.