diff --git a/lib/grade/grade_category.php b/lib/grade/grade_category.php
index 1a7497db579..a65cae84285 100644
--- a/lib/grade/grade_category.php
+++ b/lib/grade/grade_category.php
@@ -294,59 +294,63 @@ class grade_category extends grade_object {
     public function delete($source=null) {
         global $DB;
 
-        $transaction = $DB->start_delegated_transaction();
-        $grade_item = $this->load_grade_item();
+        try {
+            $transaction = $DB->start_delegated_transaction();
+            $grade_item = $this->load_grade_item();
 
-        if ($this->is_course_category()) {
+            if ($this->is_course_category()) {
 
-            if ($categories = grade_category::fetch_all(array('courseid'=>$this->courseid))) {
+                if ($categories = self::fetch_all(['courseid' => $this->courseid])) {
 
-                foreach ($categories as $category) {
+                    foreach ($categories as $category) {
 
-                    if ($category->id == $this->id) {
-                        continue; // do not delete course category yet
+                        if ($category->id == $this->id) {
+                            continue; // Do not delete course category yet.
+                        }
+                        $category->delete($source);
                     }
-                    $category->delete($source);
                 }
-            }
 
-            if ($items = grade_item::fetch_all(array('courseid'=>$this->courseid))) {
+                if ($items = grade_item::fetch_all(['courseid' => $this->courseid])) {
 
-                foreach ($items as $item) {
+                    foreach ($items as $item) {
 
-                    if ($item->id == $grade_item->id) {
-                        continue; // do not delete course item yet
+                        if ($item->id == $grade_item->id) {
+                            continue; // Do not delete course item yet.
+                        }
+                        $item->delete($source);
+                    }
+                }
+
+            } else {
+                $this->force_regrading();
+
+                $parent = $this->load_parent_category();
+
+                // Update children's categoryid/parent field first.
+                if ($children = grade_item::fetch_all(['categoryid' => $this->id])) {
+                    foreach ($children as $child) {
+                        $child->set_parent($parent->id);
+                    }
+                }
+
+                if ($children = self::fetch_all(['parent' => $this->id])) {
+                    foreach ($children as $child) {
+                        $child->set_parent($parent->id);
                     }
-                    $item->delete($source);
                 }
             }
 
-        } else {
-            $this->force_regrading();
+            // First delete the attached grade item and grades.
+            $grade_item->delete($source);
 
-            $parent = $this->load_parent_category();
+            // Delete category itself.
+            $success = parent::delete($source);
 
-            // Update children's categoryid/parent field first
-            if ($children = grade_item::fetch_all(array('categoryid'=>$this->id))) {
-                foreach ($children as $child) {
-                    $child->set_parent($parent->id);
-                }
-            }
-
-            if ($children = grade_category::fetch_all(array('parent'=>$this->id))) {
-                foreach ($children as $child) {
-                    $child->set_parent($parent->id);
-                }
-            }
+            $transaction->allow_commit();
+        } catch (Exception $e) {
+            $transaction->rollback($e);
         }
-
-        // first delete the attached grade item and grades
-        $grade_item->delete($source);
-
-        // delete category itself
-        $success = parent::delete($source);
-
-        $transaction->allow_commit();
         return $success;
     }
 
diff --git a/lib/grade/grade_grade.php b/lib/grade/grade_grade.php
index 19945633d98..e0a768466d9 100644
--- a/lib/grade/grade_grade.php
+++ b/lib/grade/grade_grade.php
@@ -1147,16 +1147,18 @@ class grade_grade extends grade_object {
      */
     public function delete($source = null) {
         global $DB;
-
-        $transaction = $DB->start_delegated_transaction();
-        $success = parent::delete($source);
-
-        // If the grade was deleted successfully trigger a grade_deleted event.
-        if ($success && !empty($this->grade_item)) {
-            \core\event\grade_deleted::create_from_grade($this)->trigger();
+        try {
+            $transaction = $DB->start_delegated_transaction();
+            $success = parent::delete($source);
+            // If the grade was deleted successfully trigger a grade_deleted event.
+            if ($success && !empty($this->grade_item)) {
+                $this->load_grade_item();
+                \core\event\grade_deleted::create_from_grade($this)->trigger();
+            }
+            $transaction->allow_commit();
+        } catch (Exception $e) {
+            $transaction->rollback($e);
         }
-
-        $transaction->allow_commit();
         return $success;
     }
 
diff --git a/lib/grade/grade_item.php b/lib/grade/grade_item.php
index a36b194caa7..ab26fb919e6 100644
--- a/lib/grade/grade_item.php
+++ b/lib/grade/grade_item.php
@@ -431,16 +431,18 @@ class grade_item extends grade_object {
     public function delete($source=null) {
         global $DB;
 
-        $transaction = $DB->start_delegated_transaction();
-        $this->delete_all_grades($source);
-        $success = parent::delete($source);
-        $transaction->allow_commit();
-
-        if ($success) {
-            $event = \core\event\grade_item_deleted::create_from_grade_item($this);
-            $event->trigger();
+        try {
+            $transaction = $DB->start_delegated_transaction();
+            $this->delete_all_grades($source);
+            $success = parent::delete($source);
+            if ($success) {
+                $event = \core\event\grade_item_deleted::create_from_grade_item($this);
+                $event->trigger();
+            }
+            $transaction->allow_commit();
+        } catch (Exception $e) {
+            $transaction->rollback($e);
         }
-
         return $success;
     }
 
@@ -453,27 +455,30 @@ class grade_item extends grade_object {
     public function delete_all_grades($source=null) {
         global $DB;
 
-        $transaction = $DB->start_delegated_transaction();
+        try {
+            $transaction = $DB->start_delegated_transaction();
 
-        if (!$this->is_course_item()) {
-            $this->force_regrading();
-        }
-
-        if ($grades = grade_grade::fetch_all(array('itemid'=>$this->id))) {
-            foreach ($grades as $grade) {
-                $grade->delete($source);
+            if (!$this->is_course_item()) {
+                $this->force_regrading();
             }
+
+            if ($grades = grade_grade::fetch_all(['itemid' => $this->id])) {
+                foreach ($grades as $grade) {
+                    $grade->delete($source);
+                }
+            }
+
+            // Delete all the historical files.
+            // We only support feedback files for modules atm.
+            if ($this->is_external_item()) {
+                $fs = new file_storage();
+                $fs->delete_area_files($this->get_context()->id, GRADE_FILE_COMPONENT, GRADE_HISTORY_FEEDBACK_FILEAREA);
+            }
+
+            $transaction->allow_commit();
+        } catch (Exception $e) {
+            $transaction->rollback($e);
         }
-
-        // Delete all the historical files.
-        // We only support feedback files for modules atm.
-        if ($this->is_external_item()) {
-            $fs = new file_storage();
-            $fs->delete_area_files($this->get_context()->id, GRADE_FILE_COMPONENT, GRADE_HISTORY_FEEDBACK_FILEAREA);
-        }
-
-        $transaction->allow_commit();
-
         return true;
     }