diff --git a/mod/assign/db/upgrade.php b/mod/assign/db/upgrade.php
index ade4b79021b..300f574d4ed 100644
--- a/mod/assign/db/upgrade.php
+++ b/mod/assign/db/upgrade.php
@@ -584,5 +584,37 @@ function xmldb_assign_upgrade($oldversion) {
     // Moodle v2.8.0 release upgrade line.
     // Put any upgrade step following this.
 
+    if ($oldversion < 2014122600) {
+        // Delete any entries from the assign_user_flags and assign_user_mapping that are no longer required.
+        if ($DB->get_dbfamily() === 'mysql') {
+            $sql1 = "DELETE {assign_user_flags}
+                       FROM {assign_user_flags}
+                  LEFT JOIN {assign}
+                         ON {assign_user_flags}.assignment = {assign}.id
+                      WHERE {assign}.id IS NULL";
+
+            $sql2 = "DELETE {assign_user_mapping}
+                       FROM {assign_user_mapping}
+                  LEFT JOIN {assign}
+                         ON {assign_user_mapping}.assignment = {assign}.id
+                      WHERE {assign}.id IS NULL";
+        } else {
+            $sql1 = "DELETE FROM {assign_user_flags}
+                WHERE NOT EXISTS (
+                          SELECT 'x' FROM {assign}
+                           WHERE {assign_user_flags}.assignment = {assign}.id)";
+
+            $sql2 = "DELETE FROM {assign_user_mapping}
+                WHERE NOT EXISTS (
+                          SELECT 'x' FROM {assign}
+                           WHERE {assign_user_mapping}.assignment = {assign}.id)";
+        }
+
+        $DB->execute($sql1);
+        $DB->execute($sql2);
+
+        upgrade_mod_savepoint(true, 2014122600, 'assign');
+    }
+
     return true;
 }
diff --git a/mod/assign/version.php b/mod/assign/version.php
index fd7b5c5c3fb..96d2675fef4 100644
--- a/mod/assign/version.php
+++ b/mod/assign/version.php
@@ -25,8 +25,6 @@
 defined('MOODLE_INTERNAL') || die();
 
 $plugin->component = 'mod_assign'; // Full name of the plugin (used for diagnostics).
-$plugin->version  = 2014111000;    // The current module version (Date: YYYYMMDDXX).
+$plugin->version  = 2014122600;    // The current module version (Date: YYYYMMDDXX).
 $plugin->requires = 2014110400;    // Requires this Moodle version.
 $plugin->cron     = 60;
-
-