diff -Nru ubuntu-release-upgrader-18.04.41/check-new-release-gtk ubuntu-release-upgrader-18.04.42/check-new-release-gtk
--- ubuntu-release-upgrader-18.04.41/check-new-release-gtk	2019-06-06 18:46:11.000000000 +0000
+++ ubuntu-release-upgrader-18.04.42/check-new-release-gtk	2020-11-30 19:09:46.000000000 +0000
@@ -38,7 +38,7 @@
 import gettext
 from optparse import OptionParser
 
-from UpdateManager.Core.utils import init_proxy
+from UpdateManager.Core.utils import init_proxy, get_arch
 
 from DistUpgrade.DistUpgradeFetcher import DistUpgradeFetcherGtk
 from UpdateManager.MetaReleaseGObject import MetaRelease
@@ -73,6 +73,7 @@
     self.options = options
     self.datadir = options.datadir
     self.new_dist = None
+    self.arch = get_arch()
     logging.debug("running with devel=%s proposed=%s" % (
             options.devel_release, options.proposed_release))
     m = MetaRelease(useDevelopmentRelease=options.devel_release,
@@ -109,9 +110,13 @@
         subprocess.call(['update-manager', '--no-update'])
         Gtk.main_quit()
     else:
-        self.build_ui()
-        self.window_main.set_title(_("Ubuntu %(version)s Upgrade Available") % {'version': new_dist.version})
-        self.window_main.show()
+        if self.arch == "i386":
+            logging.warning("There are no further Ubuntu releases for this system's 'i386' architecture.")
+            sys.exit()
+        else:
+            self.build_ui()
+            self.window_main.set_title(_("Ubuntu %(version)s Upgrade Available") % {'version': new_dist.version})
+            self.window_main.show()
 
   def close(self):
     self.window_main.destroy()
diff -Nru ubuntu-release-upgrader-18.04.41/check_new_release_gtk.py ubuntu-release-upgrader-18.04.42/check_new_release_gtk.py
--- ubuntu-release-upgrader-18.04.41/check_new_release_gtk.py	2019-06-06 18:46:11.000000000 +0000
+++ ubuntu-release-upgrader-18.04.42/check_new_release_gtk.py	2020-11-30 19:09:46.000000000 +0000
@@ -38,7 +38,7 @@
 import gettext
 from optparse import OptionParser
 
-from UpdateManager.Core.utils import init_proxy
+from UpdateManager.Core.utils import init_proxy, get_arch
 
 from DistUpgrade.DistUpgradeFetcher import DistUpgradeFetcherGtk
 from UpdateManager.MetaReleaseGObject import MetaRelease
@@ -73,6 +73,7 @@
     self.options = options
     self.datadir = options.datadir
     self.new_dist = None
+    self.arch = get_arch()
     logging.debug("running with devel=%s proposed=%s" % (
             options.devel_release, options.proposed_release))
     m = MetaRelease(useDevelopmentRelease=options.devel_release,
@@ -109,9 +110,13 @@
         subprocess.call(['update-manager', '--no-update'])
         Gtk.main_quit()
     else:
-        self.build_ui()
-        self.window_main.set_title(_("Ubuntu %(version)s Upgrade Available") % {'version': new_dist.version})
-        self.window_main.show()
+        if self.arch == "i386":
+            logging.warning("There are no further Ubuntu releases for this system's 'i386' architecture.")
+            sys.exit()
+        else:
+            self.build_ui()
+            self.window_main.set_title(_("Ubuntu %(version)s Upgrade Available") % {'version': new_dist.version})
+            self.window_main.show()
 
   def close(self):
     self.window_main.destroy()
diff -Nru ubuntu-release-upgrader-18.04.41/debian/changelog ubuntu-release-upgrader-18.04.42/debian/changelog
--- ubuntu-release-upgrader-18.04.41/debian/changelog	2020-10-26 17:23:33.000000000 +0000
+++ ubuntu-release-upgrader-18.04.42/debian/changelog	2020-11-30 19:09:46.000000000 +0000
@@ -1,3 +1,11 @@
+ubuntu-release-upgrader (1:18.04.42) bionic; urgency=medium
+
+  * check-new-release, check-new-release-gtk: Do not indicate that a release
+    upgrade is available for systems that are running on i386 architecture.
+    (LP: #1901725)
+
+ -- Brian Murray <brian@ubuntu.com>  Mon, 30 Nov 2020 11:09:46 -0800
+
 ubuntu-release-upgrader (1:18.04.41) bionic; urgency=medium
 
   [ Kyle Fazzari ]
diff -Nru ubuntu-release-upgrader-18.04.41/do-release-upgrade ubuntu-release-upgrader-18.04.42/do-release-upgrade
--- ubuntu-release-upgrader-18.04.41/do-release-upgrade	2019-11-07 11:22:02.000000000 +0000
+++ ubuntu-release-upgrader-18.04.42/do-release-upgrade	2020-11-30 19:09:42.000000000 +0000
@@ -18,7 +18,7 @@
 import subprocess
 import sys
 import time
-from UpdateManager.Core.utils import init_proxy
+from UpdateManager.Core.utils import init_proxy, get_arch
 
 RELEASE_AVAILABLE=0
 NO_RELEASE_AVAILABLE=1
@@ -140,6 +140,13 @@
     print(_("For upgrade information, please visit:\n"
             "%(url)s\n") % { 'url' : url })
 
+  if get_arch() == "i386":
+    if not options.quiet:
+      print(_("There will not be any further Ubuntu releases "))
+      print(_("for this system's 'i386' architecture. Updates for "))
+      print(_("Ubuntu 18.04 LTS will continue until April 2023."))
+    sys.exit(NO_RELEASE_AVAILABLE)
+
   # now inform about a new release
   if m.new_dist is None:
     if not options.quiet: