This might be some old news for most, but I only have a few outdoor APs and touch one every few years. But since I just got a new Cisco Aironet 1542I and was surprised again, I’d thought I document this for me. This also applies not only to the 1542, but 1532, 1552 and probably the whole outdoor portfolio, on Cisco wireless controllers.
The simple issue is: the AP is out of the box in “bridge mode”, and the controller wont let it join just that way without authenticating it. To fix, you have two possibilities: authenticate it on the controller, or switch it from bridge mode to local mode: