Upgrade to 4.0, DNS will not start, reports FTL offline

Better create you own thread as your issue seems different.
Chances are you have another DNS daemon running on ports 53 TCP/UDP, not pihole-FTL:

pi@noads:~ $ sudo netstat -nltup | grep 'Proto\|:53 \|:67 \|:80 \|:471'
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 127.0.0.1:4711          0.0.0.0:*               LISTEN      20855/pihole-FTL
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      8101/lighttpd
tcp        0      0 0.0.0.0:53              0.0.0.0:*               LISTEN      20855/pihole-FTL
tcp6       0      0 ::1:4711                :::*                    LISTEN      20855/pihole-FTL
tcp6       0      0 :::80                   :::*                    LISTEN      8101/lighttpd
tcp6       0      0 :::53                   :::*                    LISTEN      20855/pihole-FTL
udp        0      0 0.0.0.0:53              0.0.0.0:*                           20855/pihole-FTL
udp        0      0 0.0.0.0:67              0.0.0.0:*                           20855/pihole-FTL
udp6       0      0 :::53                   :::*                                20855/pihole-FTL