--- ubuntu-release-upgrader-r797ej66/DistUpgradeController.py	2016-04-07 11:24:48.000000000 -0700
+++ ubuntu-xenial-pandrew/DistUpgradeController.py	2016-08-09 12:07:21.795336070 -0700
@@ -1177,6 +1177,7 @@
             # FIXME: take this into account for diskspace calculation
             self._maybe_create_apt_btrfs_snapshot()
         res = False
+        exception = None
         while currentRetry < maxRetries:
             try:
                 res = self.cache.commit(fprogress,iprogress)
@@ -1231,11 +1232,13 @@
                 # fetch failed, will be retried
                 logging.error("IOError in cache.commit(): '%s'. Retrying (currentTry: %s)" % (e,currentRetry))
                 currentRetry += 1
+                exception = e
                 continue
             except OSError as e:
                 logging.exception("cache.commit()")
                 # deal gracefully with:
                 #  OSError: [Errno 12] Cannot allocate memory
+                exception = e
                 if e.errno == 12:
                     self._enableAptCronJob()
                     msg = _("Error during commit")
@@ -1254,7 +1257,7 @@
                          _("The upgrade has aborted. Please check your "\
                            "Internet connection or "\
                            "installation media and try again. "),
-                           "%s" % e)
+                           "%s" % exception)
         # abort here because we want our sources.list back
         self.abort()