samba - Nov 2023 - open_internal_samr_conn: Could not connect to samr pipe: NT_STATUS_CONNECTION_REFUSED

Hi

i have an issue on one server running Samba 4.16? (from Michael repo) as 
AD-DC on ubuntu 20.04.


samba runs with no error for several hours/ days

and suddenly, this issue occurs

admin user can log into domain, but fails to use windows GPO manager 
which reports that rpc server is unavailable.


winbind logs this

nov. 14 08:00:09 kwartz winbindd[3918]: [2023/11/14 08:00:09.478757, 0] 
../../source3/winbindd/winbindd_samr.c:71(open_internal_samr_conn)
nov. 14 08:00:09 kwartz winbindd[3918]: open_internal_samr_conn: Could 
not connect to samr pipe: NT_STATUS_CONNECTION_REFUSED


i also notice that wbinfo -g returns nothing


after samba-ad-dc restart, this error is gone and wbinfo -g returns all 
defined groups...


i have a quick look on sources but i did not see any logging calls that 
could help me diagnose this issue...

what should i check when this happens again?

which file path is used for samr pipe?


Thanks.


-- 
Arnaud FLORENT
IRIS Technologies