We use Falkon now, not Qupzilla (LP: #1786986).

debian/changelog

@@ -1,3 +1,9 @@
+lubuntu-default-settings (1.9) UNRELEASED; urgency=medium
+
+  * We use Falkon now, not Qupzilla (LP: #1786986).
+
+ -- Simon Quigley <tsimonq2@ubuntu.com>  Tue, 14 Aug 2018 17:25:37 -0500
+
 lubuntu-default-settings (1.8) cosmic; urgency=medium
 
   * Revert the last upload.

src/etc/xdg/xdg-Lubuntu/lxqt/panel.conf

@@ -15,7 +15,7 @@ type=desktopswitch
 [quicklaunch]
 type=quicklaunch
 apps\1\desktop=/usr/share/applications/pcmanfm-qt.desktop
-apps\2\desktop=/usr/share/applications/org.qupzilla.QupZilla.desktop
+apps\2\desktop=/usr/share/applications/org.kde.falkon.desktop
 apps\size=2
 alignment=Left
 

src/etc/xdg/xdg-Lubuntu/lxqt/session.conf

@@ -3,7 +3,7 @@ window_manager=openbox
 leave_confirmation=false
 
 [Environment]
-BROWSER=qupzilla
+BROWSER=falkon
 GTK_CSD=0
 GTK_OVERLAY_SCROLLING=0
 TERM=qterminal