diff --git a/mod/quiz/db/mysql.php b/mod/quiz/db/mysql.php
index ac46c56e080..721771a9a71 100644
--- a/mod/quiz/db/mysql.php
+++ b/mod/quiz/db/mysql.php
@@ -1035,6 +1035,11 @@ function quiz_upgrade($oldversion) {
         }
     }
 
+    if ($oldversion < 2006043000) {
+        // The newgraded field must always point to a valid state
+        modify_database("","UPDATE prefix_question_sessions SET newgraded = newest where newgraded = '0'");
+    }
+
     return true;
 }
 
diff --git a/mod/quiz/db/postgres7.php b/mod/quiz/db/postgres7.php
index 4290ed57aab..2b217c8f1eb 100644
--- a/mod/quiz/db/postgres7.php
+++ b/mod/quiz/db/postgres7.php
@@ -1206,6 +1206,11 @@ function quiz_upgrade($oldversion) {
         }
     }
 
+    if ($oldversion < 2006043000) {
+        // The newgraded field must always point to a valid state
+        modify_database("","UPDATE prefix_question_sessions SET newgraded = newest where newgraded = '0'");
+    }
+
     return true;
 }