Failed to start advertising, err -12 (-ENOMEM)

RE: Failed to start advertising, err -12 (-ENOMEM)

WoutWG — Sun, 27 Jul 2025 16:02:55 GMT

Making sure not to unref on_disconnect when acting as the peripheral indeed fixed the negative ref which caused the conn object to stay alive.

Thanks Vidar!

RE: Failed to start advertising, err -12 (-ENOMEM)

WoutWG — Tue, 22 Jul 2025 13:15:49 GMT

Hi Vidar,

Thank you for the feedback. Good to know that it's not necessary to unref the conn object in the context of being the peripheral. I currently do the unref in the on_disconnect callback which is called in both instances, for peripheral connection as well as for central connection. This would be what causes the negative reference count. I'll test a workaround to see if removing this in the peripheral connection case would solve the issue, and let you know.

Best,

Wout

RE: Failed to start advertising, err -12 (-ENOMEM)

Vidar Berg — Tue, 22 Jul 2025 11:55:34 GMT

Hello Wout,

I did not know that it was possible to get a negative reference count. But from what you describe it sounds like the problem is likely related to maintaining the correct connection reference count. For central connections, you must release the reference on disconnect since the bt_conn_le_create() takes one reference:

For peripheral connection on the other hand it is only needed if you explicitly take a reference with bt_conn_ref() on the object in your code.

[quote user=""]Alternatively, is there a way to start advertising without creating a new conn and reusing an older one?[/quote]

It can't be reused until it has been released.

It's also important that you don't try to start the advertiser immediately from the disconnect callback as the connection object will not be freed at that point. We have updated our sample codes in the more recent SDK versions to always restart the advertiser from the system workqueue.

Best regards,

Vidar