RE: Where to get the firmware error code details ??

Samruddhi Jadhav — Tue, 09 Dec 2025 13:37:56 GMT

Hi,

From your description, it seems like you are trying to call the bt_le_adv_start() function (as shown in the following Zephyr API Documentation: Generic Access Profile documentation). When you call bt_le_adv_start(), and after advertising has started, the function will return 0. If there is a fault, it will return a negative number as you are observing. The number indicates the type of error message. In the Zephyr API Documentation: Error numbers, we can see that 120 is tied with "EALREADY" (or "Operation already in process") error in the SDK. Similarly, in this documentation, we can also see which error messages the other numbers represent. If you then search for bt_le_adv_start and look into the adv.c file in the SDK, you can navigate to EALREADY (see the attached code snippet from adv.c).

	if (atomic_test_bit(adv->flags, BT_ADV_ENABLED)) {
		return -EALREADY;
	}

If you are getting -120, it indicates that you are asking to start something which has already started or already is in the running state. If it returns 0, it shows that advertising has started as per the request.

Hope this helps.