https://devzone.nordicsemi.com/f/nordic-q-a/127606/ble-sample-code-fails-to-pair-after-unpairingWe are running some sample code on the nrf54l15 mcu, specifically: /modules/lib/memfault-firmware-sdk/examples/nrf-connect-sdk/nrf5/memfault_demo_app We can connect and pair successfully (with the nRF Memfault iOS app) but then when we unpair on theen-USTelligent Community 13Fri, 10 Apr 2026 18:06:13 GMThttps://devzone.nordicsemi.com/thread/564804?ContentTypeID=1Fri, 10 Apr 2026 18:06:13 GMT137ad170-7792-4731-bb38-c0d22fbe4515:b53a8877-9e92-457b-8353-928ae48d97a3jthmp<p>ok, good to know! I guess we might need to have our mobile app send some kind of unpair request first (the button idea might not work for us).</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/564735?ContentTypeID=1Thu, 09 Apr 2026 14:54:01 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f83de56d-43b4-4626-8900-eb1bff288c89tesc<p>Hi,</p> <p>A separate way to solve the issue, is to have some mechanism on the device for deleting old bonds (for instance through using&nbsp;<a href="https://docs.nordicsemi.com/bundle/zephyr-apis-latest/page/group_bt_gap.html#gaceabbbe6e844650f791010e53c9df6a4"><code>bt_unpair()</code></a>). For instance a button on the device, a long press on an existing button, or some other form of input. This would allow the user to reset the device to a state where it will accept connections and bonds to any device. With that solution, you do not need to set the ckonfig option. Setting the option may have security implications, see <a href="https://devzone.nordicsemi.com/support-private/support/358632/Hi,%20%20%20%20%20%20Are%20there%20any%20corresponding%20examples?%20%20I%20am%20afraid%20we%20do%20not%20have%20any%20multiprotocol%20samples%20demonstrating%20concurrent%20use%20of%20Matter%20and%20Bluetooth%20Mesh.%20%20%20%20%20%20Is%20it%20feasible%20to%20run%20both%20matter%20and%20SIG%20mesh%20on%20the%20same%20chip?%20%20Feasibility%20depends%20on%20the%20type%20of%20Matter%20/%20Mesh%20devices,%20as%20well%20as%20the%20memory%20requirements%20of%20the%20application.%20%20Typical%20Bluetooth%20Mesh%20nodes%20must%20be%20in%20RX%20most%20of%20the%20time,%20in%20order%20to%20relay%20or%20receive%20messages.%20Time%20spent%20for%20Matter%20will%20impact%20negatively%20the%20ability%20of%20the%20Bluetooth%20Mesh%20node%20to%20receive%20mesh%20messages.%20Likewise,%20there%20might%20be%20degradation%20of%20Matter%20communication%20if%20a%20lot%20of%20radio%20time%20is%20spent%20for%20Bluetooth%20Mesh.%20%20In%20Bluetooth%20Mesh,%20there%20are%20also%20Low%20Power%20Nodes%20(LPN),%20which%20do%20not%20have%20the%20same%20RX%20requirements%20as%20other%20nodes.%20LPN%20nodes%20rely%20on%20a%20Friend%20node%20for%20receiving%20messages%20(but%20send%20messages%20directly.)%20Please%20note%20that%20the%20required%20Friend%20node%20does%20have%20the%20requirement%20of%20being%20in%20RX%20for%20most%20of%20the%20time.%20%20In%20Matter%20over%20Thread,%20there%20are%20Sleepy%20End%20Devivces%20(SED),%20with%20similar%20characteristics.%20%20In%20other%20words,%20if%20your%20device%20is%20a%20Bluetooth%20Mesh%20LPN%20and/or%20Matter%20Thread%20SED,%20it%20may%20be%20possible%20to%20combine%20the%20two%20without%20too%20much%20impact.%20%20%20%20%20%20Assessment%20of%20Memory%20and%20Resources?%20%20Memory%20is%20a%20concern,%20as%20both%20protocols%20may%20be%20demanding%20in%20terms%20of%20both%20non-volatile%20memory%20(RRAM%20on%20the%20nRF54L15)%20and%20RAM.%20Typical%20ballpark%20figures%20might%20reach%20around%201%20MB%20NVM%20(of%20the%201.5%20MB%20of%20RRAM)%20and%20200%20kB%20of%20RAM%20(of%20the%20256%20kB%20available),%20for%20the%20functionality%20of%20the%20two%20protocols%20combined.%20The%20number%20however%20depends%20on%20the%20type%20of%20device%20and%20the%20ballpark%20number%20is%20for%20basic%20functionality.%20I%20encourage%20you%20to%20have%20a%20look%20at%20the%20samples%20(for%20Bluetooth%20Mesh%20and%20Matter%20separately)%20to%20get%20an%20idea%20of%20the%20memory%20requirements.%20For%20a%20baseline%20roughly%20corresponding%20to%20common%20functionality%20you%20can%20use%20a%20basic%20sample%20without%20use%20of%20any%20wireless%20protocols,%20such%20as%20the%20Zephyr%20project%20blinky%20sample.%20%20Please%20note%20that%20Matter%20can%20run%20over%20both%20Thread%20and%20Zigbee,%20and%20numbers%20may%20vary%20depending%20on%20the%20underlying%20stack.%20See%20Matter%20integration%20in%20the%20nRF%20Connect%20SDK.%20%20For%20information%20on%20concurrent%20Thread/Zigbee%20(Matter)%20and%20e.g.%20BLE,%20see%20Multiprotocol%20support.%20%20Regards,%20Terje">CONFIG_BT_SMP_ALLOW_UNAUTH_OVERWRITE</a>.</p> <p>Regards,<br />Terje</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/564557?ContentTypeID=1Tue, 07 Apr 2026 18:07:41 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c37d3dea-cc67-44cb-99fd-0c3c1b30734ejthmp<p>Hi Maryproven,<br />We tried this</p> <div> <div><span>CONFIG_BT_SMP_ALLOW_UNAUTH_OVERWRITE</span><span>=y<br /></span>which seems to help, but we notice that re-connecting after pairing is very finicky and often we need to disconnect and then reconnect again.&nbsp;<br />This only happens after unpair / repair.</div> </div><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/564325?ContentTypeID=1Tue, 31 Mar 2026 16:41:45 GMT137ad170-7792-4731-bb38-c0d22fbe4515:10768b68-9b33-4071-b354-4a64771fbd60jthmp<p>Makes sense, how can I handle it automatically?</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/564229?ContentTypeID=1Mon, 30 Mar 2026 02:21:35 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a4cfb532-4b95-400d-8c2a-35c6ae9c2d5dmaryproven<p>Hello @ <a href="https://basketrandom.com">basket random</a>, you have a stale bond on the device while the phone has deleted it, so pairing fails with BT_SECURITY_ERR_AUTH_REQUIREMENT. Calling bt_unpair() works because it clears that mismatch&mdash;but you can handle it automatically instead of forcing a retry.</p><div style="clear:both;"></div>