[Samba] samba4 stopped working

[Gary Dale]

I've been using Samba4 on Debian/Jessie since it became "stable". After 
the last upgrade however, I got a massive failure.

The first symptom I noticed was that I couldn't grab updates from the 
Debian servers. However when clients tried to log in, the real problem 
revealed itself. They could only log on using a temporary profile and 
couldn't connect to any of the shares or printers.

When I test my implementation of Samba, it fails the basic test:

# smbclient -L localhost -U%
Connection to localhost failed (Error NT_STATUS_CONNECTION_REFUSED)

The globals section of smb.conf is:

[global]
         workgroup = DENTALOFFICE
         realm = DENTALOFFICE.ROSSLAND.DENTAL
         netbios name = MOLAR
         server role = active directory domain controller
         dns forwarder = 8.8.8.8
         idmap_ldb:use rfc2307 = yes
         allow dns updates = nonsecure

which explains why I can't get to the Debian servers. The hand off to 
Google's DNS servers never happens.

ps aux | grep  nmbd, smbd or samba all show that samba isn't running. 
The logs for starting samba show:

[2016/07/04 11:29:48.240042,  0] 
../source4/smbd/server.c:370(binary_smbd_main)
   samba version 4.2.10-Debian started.
   Copyright Andrew Tridgell and the Samba Team 1992-2014
[2016/07/04 11:29:48.421540,  0] 
../source4/smbd/server.c:488(binary_smbd_main)
   samba: using 'standard' process model
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
[2016/07/04 11:29:48.446253,  0] 
../lib/util/become_daemon.c:124(daemon_ready)
   STATUS=daemon 'samba' finished starting up and ready to serve connections
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
samba: setproctitle not initialized, please either call 
setproctitle_init() or link against libbsd-ctor.
[2016/07/04 11:29:48.460701,  0] 
../lib/util/util_runcmd.c:324(samba_runcmd_io_handler)
   /usr/sbin/winbindd: Failed to exec child - No such file or directory
[2016/07/04 11:29:48.462580,  0] 
../source4/winbind/winbindd.c:49(winbindd_done)
   winbindd daemon exited normally
task_server_terminate: [winbindd child process exited]
[2016/07/04 11:29:48.464159,  0] 
../source4/smbd/server.c:211(samba_terminate)
   samba_terminate: winbindd child process exited


Although the message about the daemon being ready seems to indicate that 
samba is running, as I said, ps aux shows that it isn't.

Any ideas how I can get Samba back up? Uninstalling and reinstalling it 
didn't work.