Also same here. NT4 Domain Member Server, without Winbind. Users and groups are resolved via NSS. After downgrading Samba and related packages to 2:4.7.6+dfsg~ubuntu-0ubuntu2 everything works again.
[2021/12/10 14:36:15.923981, 0] ../source3/auth/auth_util.c:1259(check_account)
check_account: Failed to convert SID S-1-5-21-1954734479-671598338-2648087304-6696 to a UID (dom_user[MYDOMAIN\myusername])
Also same here. NT4 Domain Member Server, without Winbind. Users and groups are resolved via NSS. After downgrading Samba and related packages to 2:4.7.6+ dfsg~ubuntu- 0ubuntu2 everything works again.
[2021/12/10 14:36:15.923981, 0] ../source3/ auth/auth_ util.c: 1259(check_ account) 1954734479- 671598338- 2648087304- 6696 to a UID (dom_user[ MYDOMAIN\ myusername] )
check_account: Failed to convert SID S-1-5-21-