diff --git a/admin/environment.xml b/admin/environment.xml
index 31477f927a0..916b91a10e1 100644
--- a/admin/environment.xml
+++ b/admin/environment.xml
@@ -1122,5 +1122,12 @@
         </FEEDBACK>
       </PHP_SETTING>
     </PHP_SETTINGS>
+    <CUSTOM_CHECKS>
+      <CUSTOM_CHECK file="question/engine/upgrade/upgradelib.php" function="quiz_attempts_upgraded" level="required">
+        <FEEDBACK>
+          <ON_ERROR message="quizattemptsupgradedmessage" />
+        </FEEDBACK>
+      </CUSTOM_CHECK>
+    </CUSTOM_CHECKS>
   </MOODLE>
 </COMPATIBILITY_MATRIX>
diff --git a/lang/en/admin.php b/lang/en/admin.php
index 650fd658bfe..66efc52dbaa 100644
--- a/lang/en/admin.php
+++ b/lang/en/admin.php
@@ -892,6 +892,7 @@ $string['questioncwqpfscheck'] = 'One or more \'random\' questions in a quiz are
 $string['questioncwqpfsok'] = 'Good. There are no \'random\' questions in your quizzes that are set up to select questions from a mixture of shared and unshared question categories.';
 $string['questiontype'] = 'Question type';
 $string['questiontypes'] = 'Question types';
+$string['quizattemptsupgradedmessage'] = 'In Moodle 2.1 there was a major upgrade to questions. It was possible to delay parts of the database upgrade to be run later. Before upgrading to Moodle 2.7, this upgrade must be completed.';
 $string['recaptchaprivatekey'] = 'ReCAPTCHA private key';
 $string['recaptchapublickey'] = 'ReCAPTCHA public key';
 $string['register'] = 'Register your site';
diff --git a/lib/customcheckslib.php b/lib/customcheckslib.php
index 7c63c502f79..5a155539b66 100644
--- a/lib/customcheckslib.php
+++ b/lib/customcheckslib.php
@@ -15,15 +15,16 @@
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
 /**
- * This is a one-line short description of the file
+ * This is a place to put custom environment checks, if there is not a better place.
  *
  * This library contains a collection of functions able to perform
  * some custom checks executed by environmental tests (automatically
  * executed on install & upgrade and under petition in the admin block).
  *
- * Any function in this library must return:
+ * Any function in this library gets a environment_results object passed in.
+ * It must return:
  * - null: if the test isn't relevant and must not be showed (ignored)
- * - environment_results object with the status set to:
+ * - the environment_results object that was passed in, with the status set to:
  *     - true: if passed
  *     - false: if failed
  *
diff --git a/lib/environmentlib.php b/lib/environmentlib.php
index 3d8a0dffd33..73337b2453f 100644
--- a/lib/environmentlib.php
+++ b/lib/environmentlib.php
@@ -1123,7 +1123,7 @@ class environment_results {
      */
     var $part;
     /**
-     * @var bool
+     * @var bool true means the test passed and all is OK. false means it failed.
      */
     var $status;
     /**
@@ -1180,11 +1180,11 @@ class environment_results {
     /**
      * Set the status
      *
-     * @param boolean $status the status (true/false)
+     * @param bool $testpassed true means the test passed and all is OK. false means it failed.
      */
-    function setStatus($status) {
-        $this->status=$status;
-        if ($status) {
+    function setStatus($testpassed) {
+        $this->status = $testpassed;
+        if ($testpassed) {
             $this->setErrorCode(NO_ERROR);
         }
     }
@@ -1274,7 +1274,7 @@ class environment_results {
     /**
      * Get the status
      *
-     * @return boolean result
+     * @return bool true means the test passed and all is OK. false means it failed.
      */
     function getStatus() {
         return $this->status;
diff --git a/question/engine/upgrade/upgradelib.php b/question/engine/upgrade/upgradelib.php
index 531889dbe77..9cb15e55b71 100644
--- a/question/engine/upgrade/upgradelib.php
+++ b/question/engine/upgrade/upgradelib.php
@@ -621,3 +621,32 @@ class question_deleted_question_attempt_updater extends question_qtype_attempt_u
         $data['upgradedfromdeletedquestion'] = $state->answer;
     }
 }
+
+/**
+ * This check verifies that all quiz attempts were upgraded since following
+ * the question engine upgrade in Moodle 2.1.
+ *
+ * @param environment_results object to update, if relevant.
+ * @return environment_results updated results object, or null if this test is not relevant.
+ */
+function quiz_attempts_upgraded(environment_results $result) {
+    global $DB;
+
+    $dbman = $DB->get_manager();
+    $table = new xmldb_table('quiz_attempts');
+    $field = new xmldb_field('needsupgradetonewqe');
+
+    if (!$dbman->table_exists($table) || !$dbman->field_exists($table, $field)) {
+        // DB already upgraded. This test is no longer relevant.
+        return null;
+    }
+
+    if (!$DB->record_exists('quiz_attempts', array('needsupgradetonewqe' => 1))) {
+        // No 1s present in that column means there are no problems.
+        return null;
+    }
+
+    // Only display anything if the admins need to be aware of the problem.
+    $result->setStatus(false);
+    return $result;
+}