Yesterday I upgraded from samba-4.2.3-2 to samba-4.3.0-1. Since then all three of smbd, nmbd and winbindd have failed. The best messages I got (from e.g. systemctl status smbd) said
"/usr/bin/smbd: /usr/lib/samba/libsamba-sockets-samba4.so: version `SAMBA_4.2.3' not found (required by /usr/bin/smbd)".
I tried downgrading samba, and got similar messages. Eventually I realised I had to downgrade samba, libwbclient and smbclient, all to 4.2.3, to get a working samba again. No other services seemed to be broken.
I'm afraid I don't know how to report this error, or who to, or how to fix it.
I'm running on a Raspberry Pi, uname -a gives "Linux server2 4.1.6-3-ARCH #1 PREEMPT Tue Sep 8 19:51:22 MDT 2015 armv6l GNU/Linux."