Description: corosync (2.4.3-0ubuntu1) includes an invalid debian/corosync-qdevice.init script that is used when running "systemctl enable corosync-qdevice.service", instead of using the systemd service definition. This is causing the action to fail. Removing the init script resolves the issue. Debian 9.7.0 also includes the same script, however on Debian systemctl prefers to use systemd service definitions instead of the init scripts, therefore the problem doesn't occur on debian. 
Bug: https://bugs.launchpad.net/ubuntu/+source/corosync/+bug/1809682
From: Don van der Haghen <don@haghen.com>

diff -Nru corosync-2.4.3/debian/changelog corosync-2.4.3/debian/changelog
--- corosync-2.4.3/debian/changelog	2018-04-11 18:14:52.000000000 +0200
+++ corosync-2.4.3/debian/changelog	2019-02-03 20:27:20.000000000 +0100
@@ -1,3 +1,9 @@
+corosync (2.4.3-0ubuntu2) bionic; urgency=medium
+
+  * Removed redundant/conflicting debian/corosync-qdevice.init script from package (LP: #1809682)
+
+ -- Don van der Haghen <don@haghen.com>  Sun, 03 Feb 2019 20:27:20 +0100
+
 corosync (2.4.3-0ubuntu1) bionic; urgency=medium
 
   * New upstream release (2.4.3)
diff -Nru corosync-2.4.3/debian/corosync-qdevice.init corosync-2.4.3/debian/corosync-qdevice.init
--- corosync-2.4.3/debian/corosync-qdevice.init	2018-01-31 01:40:31.000000000 +0100
+++ corosync-2.4.3/debian/corosync-qdevice.init	1970-01-01 01:00:00.000000000 +0100
@@ -1,55 +0,0 @@
-#!/bin/sh
-# kFreeBSD do not accept scripts as interpreters, using #!/bin/sh and sourcing.
-if [ true != "$INIT_D_SCRIPT_SOURCED" ] ; then
-    set "$0" "$@"; INIT_D_SCRIPT_SOURCED=true . /lib/init/init-d-script
-fi
-### BEGIN INIT INFO
-# Provides:		corosync-qdevice
-# Required-Start:	$remote_fs $syslog corosync
-# Required-Stop:	$remote_fs $syslog corosync
-# Default-Start:	
-# Default-Stop:		0 1 6
-# Short-Description:	Corosync Qdevice daemon
-# Description:		Starts and stops Corosync Qdevice daemon.
-### END INIT INFO
-
-NAME="corosync-qdevice"
-DESC="Corosync Qdevice daemon"
-DAEMON="/usr/sbin/$NAME"
-PIDFILE="/run/$NAME/$NAME.pid"
-
-CONFIG="/etc/default/$NAME"
-[ -f "$CONFIG" ] && . "$CONFIG"
-
-DAEMON_ARGS="$COROSYNC_QDEVICE_OPTIONS"
-
-do_start_prepare() {
-    if grep -q nocluster /proc/cmdline; then
-        log_failure_msg "not configured to run at boot"
-        exit 1
-    fi
-}
-
-# do_{start,stop}_cmd from init-d-script, but without the --name option.
-# corosync-qdevice is too long for a process name, it gets truncated,
-# which makes it incompatible with the --name option.  See #843419.
-do_start_cmd() {
-	start-stop-daemon --start --quiet ${PIDFILE:+--pidfile ${PIDFILE}} \
-	    $START_ARGS \
-	    --startas $DAEMON --exec $DAEMON --test > /dev/null \
-	    || return 1
-	start-stop-daemon --start --quiet ${PIDFILE:+--pidfile ${PIDFILE}} \
-	    $START_ARGS \
-	    --startas $DAEMON --exec $DAEMON -- $DAEMON_ARGS \
-	    || return 2
-}
-do_stop_cmd() {
-	start-stop-daemon --stop --quiet --retry=TERM/30/KILL/5 \
-	    $STOP_ARGS \
-	    ${PIDFILE:+--pidfile ${PIDFILE}} --exec $DAEMON
-	RETVAL="$?"
-	[ "$RETVAL" = 2 ] && return 2
-	# Many daemons don't delete their pidfiles when they exit.
-	rm -f $PIDFILE
-	return $RETVAL
-}
diff -Nru corosync-2.4.3/debian/corosync-qdevice.postinst corosync-2.4.3/debian/corosync-qdevice.postinst
--- corosync-2.4.3/debian/corosync-qdevice.postinst	1970-01-01 01:00:00.000000000 +0100
+++ corosync-2.4.3/debian/corosync-qdevice.postinst	2019-02-03 20:27:20.000000000 +0100
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+set -e
+
+# For upgrades from older corosync-qdevice version, delete redundant/conflicting init file (LP: #1809682)
+if [ "$1" = "configure" ] && [ -e "/etc/init.d/corosync-qdevice" ] ; then
+	rm -f "/etc/init.d/corosync-qdevice"
+fi
+
+#DEBHELPER#