Bonding between nrf54L15 and nrf52810 failed

RE: Bonding between nrf54L15 and nrf52810 failed

ilockit_CFR — Mon, 22 Dec 2025 09:57:20 GMT

Thank you very much, that solved the issue. I wasn't aware of this when migrating to NCS SDK 3.1.0.

RE: Bonding between nrf54L15 and nrf52810 failed

Vidar Berg — Mon, 22 Dec 2025 09:46:38 GMT

Thank you Turbo J , you are completely right. I did not think of this. Here's a link to migration document for reference: https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/releases_and_maturity/migration/migration_guide_3.0.html#bluetooth_le_legacy_pairing

RE: Bonding between nrf54L15 and nrf52810 failed

Turbo J — Mon, 22 Dec 2025 09:30:13 GMT

Incompatible and insecure configuration.

Newer (3.x.y) NCS SDKs have deactivated bonding support for sec_param.lesc = 0; configured BTLE devices, those are no longer considered secure.

You can still turn this on manually with a configuration option, I believe its in the SDK upgrade/release notes documentation somewhere.

RE: Bonding between nrf54L15 and nrf52810 failed

ilockit_CFR — Mon, 22 Dec 2025 09:09:49 GMT

Hello Vidar,

I'm registering only these three callbacks and the connection callback "connected", "disconnected" and "security_changed". I get the following debug output when connecting to the peripheral:

I: Connected (connected callback)
D: bt_conn_set_security = 0 (connected callback)
D: Security changed: C1:96:E9:FC:D7:90 (random) level 1 (security_changed callback)
D: Pairing failed conn: C1:96:E9:FC:D7:90 (random), reason 4 (pairing_failed callback)

Do you have an idea why the security level changed to level 1 instead of level 2?

Best regards,

Christian

RE: Bonding between nrf54L15 and nrf52810 failed

Vidar Berg — Wed, 17 Dec 2025 09:32:34 GMT

Hello Christian,

It seems like the peripheral is failing to meet the authentication requirements from the central. Please try to only register the authentication callbacks show in picture below taken from the central_uart sample. Registering other callbacks such as "pairing_confirm" will imply user IO and MITM support. If it is possible to attach a debugger or get debug logs from the nrf54l central, please also check the error reported in the pairing failed callback.

Best regards,

Vidar