uname -a 13.0-CURRENT FreeBSD 13.0-CURRENT #11 9e4440ca5ba-c273667(master)-dirty: Sat Dec 26 05:49:32 JST 2020 That smbfs is used in autofs, at shutdown or a reboot coredump. <Setting of smbfs.> samba -fstype=smbfs,-f=644,-d=755,-u=1001,-g=1001 ://XXXXXXX@XXXXX/xxx It'll be probably Device busy, and, umount Can, I think like the cause. A module of a possibility with the problem is written. kldstat (Something related) smbfs.ko libiconv.ko libmchain.ko coredump , So, how to take it log isn't understood. Could you try whether you reappear? It'll be 100 % by my environment. Thank you.