iwn0: fatal firmware error after sysupgrade to 7.1

Please CC me. I am not subscribed to the list.

Hello,

after upgrading from 7.0 to 7.1, the iwn0 interface cannot be used
anymore, stating iwn0: fatal firmware error. I then checked out 7.1
stable, build the GENERIC.MP kernel, the system and xenocara. Issue
remains. Here's what dmesg contains after adding the "debug" option to
/etc/hostname.iwn0.

Thanks for any help.

splassert: ieee80211_free_node: want 7 have 4
urtw0 detached
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: fatal firmware error
iwn0: SCAN -> AUTH
iwn0: sending auth to c8:0e:14:ea:23:83 on channel 13 mode 11g
iwn0: fatal firmware error
firmware error log:
error type = "SYSASSERT" (0x00000005)
program counter = 0x0001DFB0
source line = 0x000001FB
error data = 0x000001FB00000009
branch link = 0x0001DF940001DF94
interrupt link = 0x0000091600000000
time = 3432666
driver status:
tx ring 0: qid=0 cur=1 queued=1
tx ring 1: qid=1 cur=0 queued=0
tx ring 2: qid=2 cur=0 queued=0
tx ring 3: qid=3 cur=0 queued=0
tx ring 4: qid=4 cur=30 queued=0
tx ring 5: qid=5 cur=0 queued=0
tx ring 6: qid=6 cur=0 queued=0
tx ring 7: qid=7 cur=0 queued=0
tx ring 8: qid=8 cur=0 queued=0
tx ring 9: qid=9 cur=0 queued=0
tx ring 10: qid=10 cur=0 queued=0
tx ring 11: qid=11 cur=0 queued=0
tx ring 12: qid=12 cur=0 queued=0
tx ring 13: qid=13 cur=0 queued=0
tx ring 14: qid=14 cur=0 queued=0
tx ring 15: qid=15 cur=0 queued=0
tx ring 16: qid=16 cur=0 queued=0
tx ring 17: qid=17 cur=0 queued=0
tx ring 18: qid=18 cur=0 queued=0
tx ring 19: qid=19 cur=0 queued=0
rx ring: cur=49
802.11 state 2
iwn0: AUTH -> INIT
iwn0: begin active scan
iwn0: INIT -> SCAN