diff --git a/lib/questionlib.php b/lib/questionlib.php
index 23325c85bed..d78a84da98e 100644
--- a/lib/questionlib.php
+++ b/lib/questionlib.php
@@ -940,23 +940,18 @@ function question_load_questions($questionids, $extrafields = '', $join = '') {
  * @param stdClass[]|null $filtercourses The courses to filter the course tags by.
  */
 function _tidy_question($question, $category, array $tagobjects = null, array $filtercourses = null): void {
-    // Load question-type specific fields.
-    if (!question_bank::is_qtype_installed($question->qtype)) {
-        $question->questiontext = html_writer::tag('p', get_string('warningmissingtype',
-                'qtype_missingtype')) . $question->questiontext;
-    }
-
-    // Convert numeric fields to float (Prevents these being displayed as 1.0000000.).
+    // Convert numeric fields to float. This prevents these being displayed as 1.0000000.
     $question->defaultmark += 0;
     $question->penalty += 0;
 
+    // Indicate the question is now fully initialised.
     if (isset($question->_partiallyloaded)) {
         unset($question->_partiallyloaded);
     }
 
     $question->categoryobject = $category;
-    question_bank::get_qtype($question->qtype)->get_question_options($question);
 
+    // Add any tags we have been passed.
     if (!is_null($tagobjects)) {
         $categorycontext = context::instance_by_id($category->contextid);
         $sortedtagobjects = question_sort_tags($tagobjects, $categorycontext, $filtercourses);
@@ -965,6 +960,14 @@ function _tidy_question($question, $category, array $tagobjects = null, array $f
         $question->tagobjects = $sortedtagobjects->tagobjects;
         $question->tags = $sortedtagobjects->tags;
     }
+
+    // Load question-type specific fields.
+    if (question_bank::is_qtype_installed($question->qtype)) {
+        question_bank::get_qtype($question->qtype)->get_question_options($question);
+    } else {
+        $question->questiontext = html_writer::tag('p', get_string('warningmissingtype',
+                'qtype_missingtype')) . $question->questiontext;
+    }
 }
 
 /**
diff --git a/mod/quiz/classes/question/bank/qbank_helper.php b/mod/quiz/classes/question/bank/qbank_helper.php
index fd6cdbf4ef8..f558d4e996a 100644
--- a/mod/quiz/classes/question/bank/qbank_helper.php
+++ b/mod/quiz/classes/question/bank/qbank_helper.php
@@ -183,7 +183,6 @@ class qbank_helper {
                 $slot->category = 0;
                 $slot->qtype = 'missingtype';
                 $slot->name = get_string('missingquestion', 'quiz');
-                $slot->maxmark = 0;
                 $slot->questiontext = ' ';
                 $slot->questiontextformat = FORMAT_HTML;
                 $slot->length = 1;
diff --git a/mod/quiz/report/reportlib.php b/mod/quiz/report/reportlib.php
index 592b41b37ad..ff17ccfcafb 100644
--- a/mod/quiz/report/reportlib.php
+++ b/mod/quiz/report/reportlib.php
@@ -95,7 +95,6 @@ function quiz_has_questions($quizid) {
  *      ->slot, ->id, ->qtype, ->length, ->number, ->maxmark, ->category (for random questions).
  */
 function quiz_report_get_significant_questions($quiz) {
-    global $DB;
     $quizobj = mod_quiz\quiz_settings::create($quiz->id);
     $structure = \mod_quiz\structure::create_for_quiz($quizobj);
     $slots = $structure->get_slots();
diff --git a/mod/quiz/report/statistics/report.php b/mod/quiz/report/statistics/report.php
index ddd52a9e82c..3ca430e539b 100644
--- a/mod/quiz/report/statistics/report.php
+++ b/mod/quiz/report/statistics/report.php
@@ -835,33 +835,29 @@ class quiz_statistics_report extends report_base {
     public function load_and_initialise_questions_for_calculations($quiz) {
         // Load the questions.
         $questions = quiz_report_get_significant_questions($quiz);
-        $questionids = [];
-        $randomquestions = [];
+        $questiondata = [];
         foreach ($questions as $qs => $question) {
             if ($question->qtype === 'random') {
                 $question->id = 0;
                 $question->name = get_string('random', 'quiz');
                 $question->questiontext = get_string('random', 'quiz');
                 $question->parenttype = 'random';
-                $randomquestions [] = $question;
-                unset($questions[$qs]);
-                continue;
+                $questiondata[$question->slot] = $question;
+            } else if ($question->qtype === 'missingtype') {
+                $question->id = is_numeric($question->id) ? (int) $question->id : 0;
+                $questiondata[$question->slot] = $question;
+                $question->name = get_string('deletedquestion', 'qtype_missingtype');
+                $question->questiontext = get_string('deletedquestiontext', 'qtype_missingtype');
+            } else {
+                $q = question_bank::load_question_data($question->id);
+                $q->maxmark = $question->maxmark;
+                $q->slot = $question->slot;
+                $q->number = $question->number;
+                $q->parenttype = null;
+                $questiondata[$question->slot] = $q;
             }
-            $questionids[] = $question->id;
         }
-        $fullquestions = question_load_questions($questionids);
-        foreach ($questions as $qno => $question) {
-            $q = $fullquestions[$question->id];
-            $q->maxmark = $question->maxmark;
-            $q->slot = $question->slot;
-            $q->number = $question->number;
-            $q->parenttype = null;
-            $questiondata[$question->slot] = $q;
-        }
-        foreach ($randomquestions as $randomquestion) {
-            $questiondata[$randomquestion->slot] = $randomquestion;
-        }
-        ksort($questiondata);
+
         return $questiondata;
     }
 
diff --git a/mod/quiz/report/statistics/statistics_table.php b/mod/quiz/report/statistics/statistics_table.php
index f0f3e1a6174..4a5eacd9b27 100644
--- a/mod/quiz/report/statistics/statistics_table.php
+++ b/mod/quiz/report/statistics/statistics_table.php
@@ -201,6 +201,8 @@ class quiz_statistics_table extends flexible_table {
     protected function col_actions($questionstat) {
         if ($this->is_calculated_question_summary($questionstat)) {
             return '';
+        } else if ($questionstat->question->qtype === 'missingtype') {
+            return '';
         } else {
             $random = null;
             if ($questionstat->question->qtype === 'random') {
diff --git a/mod/quiz/report/statistics/tests/behat/missing_questions.feature b/mod/quiz/report/statistics/tests/behat/missing_questions.feature
new file mode 100644
index 00000000000..875b57a6a14
--- /dev/null
+++ b/mod/quiz/report/statistics/tests/behat/missing_questions.feature
@@ -0,0 +1,48 @@
+@mod @mod_quiz @quiz @quiz_statistics
+Feature: Robustness of the statistics calculations with missing qusetions
+  In order to be able to install and uninstall plugins
+  As a teacher
+  I need the statistics to work even if a question type has been uninstalled
+
+  Scenario: Statistics can be calculated even after a question type has been uninstalled
+    Given the following "users" exist:
+      | username |
+      | teacher  |
+      | student  |
+    And the following "courses" exist:
+      | fullname | shortname |
+      | Course 1 | C1        |
+    And the following "course enrolments" exist:
+      | user    | course | role           |
+      | teacher | C1     | editingteacher |
+      | student | C1     | student        |
+    And the following "question categories" exist:
+      | contextlevel | reference | name           |
+      | Course       | C1        | Test questions |
+    And the following "questions" exist:
+      | questioncategory | qtype     | name            |
+      | Test questions   | truefalse | Test question 1 |
+      | Test questions   | truefalse | Test question 2 |
+    And the following "activities" exist:
+      | activity   | name   | course | idnumber |
+      | quiz       | Quiz 1 | C1     | quiz1    |
+    And quiz "Quiz 1" contains the following questions:
+      | question        | page |
+      | Test question 1 | 1    |
+      | Test question 2 | 1    |
+    And user "student" has attempted "Quiz 1" with responses:
+      | slot | response |
+      |   1  | True     |
+      |   2  | True     |
+    And question "Test question 1" is changed to simulate being of an uninstalled type
+    And question "Test question 2" no longer exists in the database
+
+    When I am on the "Quiz 1" "mod_quiz > Statistics report" page logged in as teacher
+
+    Then I should see "Quiz structure analysis"
+    And "1" row "Question name" column of "questionstatistics" table should contain "Missing question"
+    And "1" row "Attempts" column of "questionstatistics" table should contain "1"
+    And "1" row "Intended weight" column of "questionstatistics" table should contain "50.00%"
+    And "2" row "Question name" column of "questionstatistics" table should contain "Missing question"
+    And "2" row "Attempts" column of "questionstatistics" table should contain "1"
+    And "2" row "Intended weight" column of "questionstatistics" table should contain "50.00%"
diff --git a/mod/quiz/report/statistics/tests/behat/random_essays.feature b/mod/quiz/report/statistics/tests/behat/random_essays.feature
new file mode 100644
index 00000000000..1cc460cee6b
--- /dev/null
+++ b/mod/quiz/report/statistics/tests/behat/random_essays.feature
@@ -0,0 +1,38 @@
+@mod @mod_quiz @quiz @quiz_statistics
+Feature: Robustness of the statistics calculations with random essays
+  In order not to see errors
+  As a teacher
+  I need the statistics to work even if the quiz uses a random selection of essays
+
+  Scenario: Statistics can be calculated even after a question type has been uninstalled
+    Given the following "users" exist:
+      | username |
+      | teacher  |
+      | student  |
+    And the following "courses" exist:
+      | fullname | shortname |
+      | Course 1 | C1        |
+    And the following "course enrolments" exist:
+      | user    | course | role           |
+      | teacher | C1     | editingteacher |
+      | student | C1     | student        |
+    And the following "question categories" exist:
+      | contextlevel | reference | name           |
+      | Course       | C1        | Test questions |
+    And the following "questions" exist:
+      | questioncategory | qtype  | template                | name                    | questiontext |
+      | Test questions   | essay  | plain                   | Test question 1         |              |
+      | Test questions   | essay  | plain                   | Test question 2         |              |
+      | Test questions   | random |                         | Random (Test questions) | 0            |
+    And the following "activities" exist:
+      | activity   | name   | course | idnumber |
+      | quiz       | Quiz 1 | C1     | quiz1    |
+    And quiz "Quiz 1" contains the following questions:
+      | question                | page |
+      | Random (Test questions) | 1    |
+    And user "student" has attempted "Quiz 1" with responses:
+      | slot | response                   |
+      |   1  | Here is my wonderful essay |
+
+    When I am on the "Quiz 1" "mod_quiz > Statistics report" page logged in as teacher
+    Then I should see "No attempts have been made at this quiz, or all attempts have questions that need manual grading."
diff --git a/question/classes/statistics/questions/all_calculated_for_qubaid_condition.php b/question/classes/statistics/questions/all_calculated_for_qubaid_condition.php
index 50279857726..4fca96f8b79 100644
--- a/question/classes/statistics/questions/all_calculated_for_qubaid_condition.php
+++ b/question/classes/statistics/questions/all_calculated_for_qubaid_condition.php
@@ -26,6 +26,8 @@
 
 namespace core_question\statistics\questions;
 
+use question_bank;
+
 /**
  * A collection of all the question statistics calculated for an activity instance.
  *
@@ -214,7 +216,13 @@ class all_calculated_for_qubaid_condition {
                 } else {
                     $this->subquestionstats[$fromdb->questionid] = new calculated_for_subquestion();
                     $this->subquestionstats[$fromdb->questionid]->populate_from_record($fromdb);
-                    $this->subquestionstats[$fromdb->questionid]->question = $this->subquestions[$fromdb->questionid];
+                    if (isset($this->subquestions[$fromdb->questionid])) {
+                        $this->subquestionstats[$fromdb->questionid]->question =
+                                $this->subquestions[$fromdb->questionid];
+                    } else {
+                        $this->subquestionstats[$fromdb->questionid]->question =
+                                question_bank::get_qtype('missingtype', false)->make_deleted_instance($fromdb->questionid, 1);
+                    }
                 }
             }
         }
diff --git a/question/tests/behat/behat_core_question.php b/question/tests/behat/behat_core_question.php
index 601d2f884c3..b9252e2e56e 100644
--- a/question/tests/behat/behat_core_question.php
+++ b/question/tests/behat/behat_core_question.php
@@ -249,4 +249,54 @@ class behat_core_question extends behat_question_base {
         $this->execute("behat_general::i_click_on",
             ["#bulkactionsui-container input[name='$action']", "css_element"]);
     }
+
+    /**
+     * Change the question type of the give question to a type that does not exist.
+     *
+     * This is useful for testing robustness of the code when a question type
+     * has been uninstalled, even though there are still questions of that type
+     * or attempts at them.
+     *
+     * In order to set things up, you probably need to start by generating
+     * questions of a valid type, then using this to change the type once the
+     * data is created.
+     *
+     * @Given question :questionname is changed to simulate being of an uninstalled type
+     * @param string $questionname the question name.
+     */
+    public function change_question_to_nonexistant_type($questionname) {
+        global $DB;
+        [$id] = $this->find_question_by_name($questionname);
+
+        // Check our assumption.
+        $nonexistanttype = 'invalidqtype';
+        if (question_bank::is_qtype_installed($nonexistanttype)) {
+            throw new coding_exception('This code assumes that the qtype_' . $nonexistanttype .
+                    ' is not a valid plugin name, but that plugin now seems to exist!');
+        }
+
+        $DB->set_field('question', 'qtype', $nonexistanttype, ['id' => $id]);
+        question_bank::notify_question_edited($id);
+    }
+
+    /**
+     * Forcibly delete a question from the database.
+     *
+     * This is useful for testing robustness of the code when a question
+     * record is no longer in the database, even though it is referred to.
+     * Obviously, this should never happen, but it has been known to in the past
+     * and so we sometimes need to be able to test the code can handle this situation.
+     *
+     * In order to set things up, you probably need to start by generating
+     * a valid questions, then using this to remove it once the data is created.
+     *
+     * @Given question :questionname no longer exists in the database
+     * @param string $questionname the question name.
+     */
+    public function remove_question_from_db($questionname) {
+        global $DB;
+        [$id] = $this->find_question_by_name($questionname);
+        $DB->delete_records('question', ['id' => $id]);
+        question_bank::notify_question_edited($id);
+    }
 }
diff --git a/question/type/essay/question.php b/question/type/essay/question.php
index 9d331f67b93..5d9b6d03893 100644
--- a/question/type/essay/question.php
+++ b/question/type/essay/question.php
@@ -111,11 +111,15 @@ class qtype_essay_question extends question_with_responses {
     }
 
     public function un_summarise_response(string $summary) {
-        if (!empty($summary)) {
-            return ['answer' => text_to_html($summary)];
-        } else {
+        if (empty($summary)) {
             return [];
         }
+
+        if (str_contains($this->responseformat, 'editor')) {
+            return ['answer' => text_to_html($summary), 'answerformat' => FORMAT_HTML];
+        } else {
+            return ['answer' => $summary, 'answerformat' => FORMAT_PLAIN];
+        }
     }
 
     public function get_correct_response() {