All 20 of my 205 AP's bark this message once a minute:
03-08-2017 16:55:40 Local1.Error 172.21.1.217 Mar 8 16:55:40 2017 172.21.1.217 stm[1787]: <304055> <ERRS> <172.21.1.217 AC:A3:1E:C1:DD:3A> |ap| Unexpected stm (Station management) runtime error at wifi_mgmt_recv_frame, 7282, wifi_mgmt_recv_frame:7282: NULL src-mac, frame type=0, subtype=15
I can't find any reference to it in the forums, nor can I match it up to anything in Airwave. We're on Airwave 8.2.3 and Controller is on 6.4.2.0-4.1.1.0_45444.