diff -Nru bacula-9.4.2/debian/bacula-sd.postinst bacula-9.4.2/debian/bacula-sd.postinst
--- bacula-9.4.2/debian/bacula-sd.postinst	2019-03-01 04:45:37.000000000 +0000
+++ bacula-9.4.2/debian/bacula-sd.postinst	2020-04-13 22:05:09.000000000 +0000
@@ -14,13 +14,15 @@
 
 	# create new bacula-sd.conf using the template
 	TMP_CONFIG="$(mktemp -p /tmp $PKG_NAME.conf.ucftmp-XXXXXXXXXX)"
-	chmod 640 $TMP_CONFIG
-	chown bacula:bacula $TMP_CONFIG
-
 	sed -e s~@debian_basename@~`hostname`~ \
 	    -e s~XXX_SDPASSWORD_XXX~$SDPASSWD~ \
 	    -e s~XXX_MONSDPASSWORD_XXX~$SDMPASSWD~ \
 	    $TEMPLATE > $TMP_CONFIG
+
+	# set permissions
+	chmod 640 $TMP_CONFIG
+	chown bacula:bacula $TMP_CONFIG
+
 	# let ucf handle the conffile and register it
 	ucf --debconf-ok --three-way $TMP_CONFIG $TARGET
 	ucfr $PKG_NAME $TARGET
diff -Nru bacula-9.4.2/debian/changelog bacula-9.4.2/debian/changelog
--- bacula-9.4.2/debian/changelog	2020-03-22 15:34:17.000000000 +0000
+++ bacula-9.4.2/debian/changelog	2020-04-13 22:05:09.000000000 +0000
@@ -1,3 +1,14 @@
+bacula (9.4.2-2ubuntu5) focal; urgency=medium
+
+  * d/bacula-sd.postinst: let root user modify $TMP_CONFIG file
+    (LP: #1861514). Currently, the root user tries to modify the $TMP_CONFIG
+    file and it gets a permission denied error because the persmission and owner
+    is changed before any modification in this file is applied. Letting root
+    user modify $TMP_CONFIG first and then set the permissions fix this
+    installation issue.
+
+ -- Lucas Kanashiro <lucas.kanashiro@canonical.com>  Mon, 13 Apr 2020 19:05:09 -0300
+
 bacula (9.4.2-2ubuntu4) focal; urgency=medium
 
   * No-change rebuild for libgcc-s1 package name change.