https://devzone.nordicsemi.com/f/nordic-q-a/25485/when-i-joined-two-project-i-have-error-undefined-symbol-ble_nus_initWhen I joined project &quot;1. ble_app_uart&quot; and &quot;ble_app_hrs_nfc_pairing&quot; I have error after compiling project. ._build\nrf52832_xxaa.axf: Error: L6218E: Undefined symbol ble_nus_init (referred from main.o). ._build\nrf52832_xxaa.axf: Error: L6218E: Undefineden-USTelligent Community 13Tue, 26 Sep 2017 13:31:55 GMThttps://devzone.nordicsemi.com/thread/100426?ContentTypeID=1Tue, 26 Sep 2017 13:31:55 GMT137ad170-7792-4731-bb38-c0d22fbe4515:dacf5e46-029e-43b9-a9c0-e9bc3b8f8e7aaudiya<p>I found mistake. I forgotten enable &quot;BLE_NUS_ENABLED&quot; in sdk_config.h.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/100425?ContentTypeID=1Tue, 26 Sep 2017 12:52:16 GMT137ad170-7792-4731-bb38-c0d22fbe4515:626bbec5-588c-4f2c-8520-108409e53227MartinBL<p>It looks like you have forgotten to add the ble_nus.c file in your project. You can find the file in the folder &quot;your_sdk\components\ble\ble_services\ble_nus&quot;.</p><div style="clear:both;"></div>