** Samba has released 4.4.4 on June 7, 2016 and this version should work when you are upgrading from 4.4.3 **
I upgraded my test CentOS with Samba 4.4.2 AD DC to Samba 4.4.3 and it failed, and I can not login in my domain.
Checking the see if AD DC works, the first test fails and all the other tests complete succesfully.
$smbclient -L localhost -U% Domain=[BALES] OS=[Windows 6.1] Server=[Samba 4.4.3] tree connect failed: NT_STATUS_CONNECTION_DISCONNECTED
To get it work as a domain I first did a backup of my domain, then I deleted the smb.conf file, I rebuilt my domain used samba-tool and using my own instructions I did a restored my last backup, and it works.
My test Linux Mint has the same test failed and I can not login into the domain. I did the same thing as with CentOS (backup, deleted my smb.conf file, rebuilt my domain and restored) and it works.
I checked Samba bug reports and even though I can’t find one with upgrading to 4.4.3, there is bug about it’s not completing compiling and errors https://bugzilla.samba.org/show_bug.cgi?id=11891