[Samba] Failed to find a writeable DC

[Fabrizio Rompani]

could be a version incompatibility issue? 
thank's 
rf


----- Messaggio originale -----
Da: "Fabrizio Rompani via samba" <samba at lists.samba.org>
A: "samba" <samba at lists.samba.org>
Inviato: Mercoledì, 8 ottobre 2025 22:44:19
Oggetto: [Samba] Failed to find a writeable DC

hi all 
I have a DC used to manage user authentication to nextcloud app installed on the same server. 
I moved NC to a new server leaving samba-ad-dc on the old one ( appropriate firewall rules exits ) 
Now I want to move samba to new VM so I can shutdown the old one. 

To do so ,I'm trying to join a second DC installed to the new machine and then , after move all roles , I can demote and switch off the old VM. 

BUT : when I try to join the second DC 
I got this : 
root at grants-dc:~# samba-tool domain join s4ad.domain.org DC -U administrator --realm=S4AD.CESVI.ORG -W S4AD 
INFO 2025-10-08 22:29:30,946 pid:3292 /usr/lib/python3/dist-packages/samba/join.py #106: Finding a writeable DC for domain 's4ad.domain.org' 
ERROR: Failed to find a writeable DC for domain 's4ad.domain.org': The object was not found. 


Here my config files: 



    * Actual (unique) DC : Ubuntu 20.04 , samba 4.15.13 

hosts: 
xx.xx.xx.xx grants.s4ad.domain.org 

krb5.conf: 
[libdefaults] 
default_realm = S4AD.DOMAIN.ORG 
dns_lookup_kdc = true 
dns_lookup_realm = false 

smb.conf 
[global] 
dns forwarder = 127.0.0.1 
netbios name = GRANTS 
realm = S4AD.DOMAIN.ORG 
server role = active directory domain controller 
workgroup = S4AD 
server services = -dns 
interfaces = eth0 lo 
bind interfaces only = yes 



    * New DC Ubuntu 24.04 samba 4.23 

hosts: 
yy.yy.yy.yy grants-dc.s4ad.domain.org 

/etc/netplan/ 

network: 
version: 2 
ethernets: 
ens18: 
addresses: 
- "yy.yy.yy.yy/24" 
nameservers: 
addresses: 
- xx.xx.xx.xx 
search: [] 






    * dig grants.s4ad.domain.org 

grants.s4ad.domain.org. 0 IN A xx.xx.xx.xx 





    * root at grants-dc:~# host -t SRV _ldap._tcp.dc._msdcs.s4ad.domain.org 

_ldap._tcp.dc._msdcs.s4ad.domain.org has SRV record 0 100 389 grants.s4ad.domain.org. 




    * root at grants-dc:~# ping grants.s4ad.domain.org 

PING grants.s4ad.domain.org (89.116.29.118) 56(84) bytes of data. 
64 bytes from grants.s4ad.domain.org (xx.xx.xx.xx): icmp_seq=1 ttl=53 time=280 ms 
64 bytes from grants.s4ad.domain.org (xx.xx.xx.xx): icmp_seq=2 ttl=53 time=290 ms 
^C 



any hints ? 
thank's 
rf 



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Questo messaggio e' riservato ai destinatari indicati e contiene informazioni confidenziali, ivi compresi gli allegati.E' vietata la diffusione, copia o utilizzo non autorizzato. Se lo ha ricevuto per errore, La invitiamo a eliminarlo immediatamente  e a informarci tempestivamente. Grazie.

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