diff --git a/lib/classes/task/manager.php b/lib/classes/task/manager.php
index b9ef74ee7ddc5..befe2af8cb742 100644
--- a/lib/classes/task/manager.php
+++ b/lib/classes/task/manager.php
@@ -229,6 +229,7 @@ public static function configure_scheduled_task(scheduled_task $task) {
         $record = self::record_from_scheduled_task($task);
         $record->id = $original->id;
         $record->nextruntime = $task->get_next_scheduled_time();
+        unset($record->lastruntime);
         $result = $DB->update_record('task_scheduled', $record);
 
         return $result;
diff --git a/lib/tests/scheduled_task_test.php b/lib/tests/scheduled_task_test.php
index 3246b6dd9f0ab..d57c352ec6d5a 100644
--- a/lib/tests/scheduled_task_test.php
+++ b/lib/tests/scheduled_task_test.php
@@ -732,4 +732,24 @@ public function assertTaskNotEquals(\core\task\task_base $task, \core\task\task_
 
         call_user_func_array([$this, 'assertNotEquals'], $args);
     }
+
+    /**
+     * Assert that the lastruntime column holds an original value after a scheduled task is reset.
+     */
+    public function test_reset_scheduled_tasks_for_component_keeps_original_lastruntime(): void {
+        global $DB;
+        $this->resetAfterTest(true);
+
+        // Set lastruntime for the scheduled task.
+        $DB->set_field('task_scheduled', 'lastruntime', 123456789, ['classname' => '\core\task\session_cleanup_task']);
+
+        // Reset the task.
+        \core\task\manager::reset_scheduled_tasks_for_component('moodle');
+
+        // Fetch the task again.
+        $taskafterreset = \core\task\manager::get_scheduled_task(core\task\session_cleanup_task::class);
+
+        // Confirm, that lastruntime is still in place.
+        $this->assertEquals(123456789, $taskafterreset->get_last_run_time());
+    }
 }
diff --git a/mod/assign/locallib.php b/mod/assign/locallib.php
index ce652aa99334e..0697d541d13b3 100644
--- a/mod/assign/locallib.php
+++ b/mod/assign/locallib.php
@@ -2518,7 +2518,8 @@ public static function cron() {
         // Only ever send a max of one days worth of updates.
         $yesterday = time() - (24 * 3600);
         $timenow   = time();
-        $lastruntime = $DB->get_field('task_scheduled', 'lastruntime', array('component' => 'mod_assign'));
+        $task = \core\task\manager::get_scheduled_task(mod_assign\task\cron_task::class);
+        $lastruntime = $task->get_last_run_time();
 
         // Collect all submissions that require mailing.
         // Submissions are included if all are true:
diff --git a/mod/assign/tests/locallib_test.php b/mod/assign/tests/locallib_test.php
index 8c51acbebc1ac..0d5af67cdc56e 100644
--- a/mod/assign/tests/locallib_test.php
+++ b/mod/assign/tests/locallib_test.php
@@ -4206,4 +4206,54 @@ public function test_view_group_override() {
         $output3 .= $assign->get_renderer()->render($summary);
         $this->assertStringContainsStringIgnoringCase('Friday, 7 June 2019, 5:37 PM', $output3);
     }
+
+    /**
+     * Test that cron task uses task API to get its last run time.
+     */
+    public function test_cron_use_task_api_to_get_lastruntime() {
+        global $DB;
+        $this->resetAfterTest();
+        $course = $this->getDataGenerator()->create_course();
+
+        // Create an assignment which allows submissions from 3 days ago.
+        $assign1 = $this->create_instance($course, [
+            'duedate' => time() + DAYSECS,
+            'alwaysshowdescription' => 0,
+            'allowsubmissionsfromdate' => time() - 3 * DAYSECS,
+            'intro' => 'This one should not be re-created',
+        ]);
+
+        // Create an assignment which allows submissions from 1 day ago.
+        $assign2 = $this->create_instance($course, [
+            'duedate' => time() + DAYSECS,
+            'alwaysshowdescription' => 0,
+            'allowsubmissionsfromdate' => time() - DAYSECS,
+            'intro' => 'This one should be re-created',
+        ]);
+
+        // Set last run time 2 days ago.
+        $DB->set_field('task_scheduled', 'lastruntime', time() - 2 * DAYSECS, ['classname' => '\mod_assign\task\cron_task']);
+
+        // Remove events to make sure cron will update calendar and re-create one of them.
+        $params = array('modulename' => 'assign', 'instance' => $assign1->get_instance()->id);
+        $DB->delete_records('event', $params);
+        $params = array('modulename' => 'assign', 'instance' => $assign2->get_instance()->id);
+        $DB->delete_records('event', $params);
+
+        // Run cron.
+        assign::cron();
+
+        // Assert that calendar hasn't been updated for the first assignment as it's supposed to be
+        // updated as part of previous cron runs (allowsubmissionsfromdate is less than lastruntime).
+        $params = array('modulename' => 'assign', 'instance' => $assign1->get_instance()->id);
+        $event1 = $DB->get_record('event', $params);
+        $this->assertEmpty($event1);
+
+        // Assert that calendar has been updated for the second assignment
+        // because its allowsubmissionsfromdate is greater than lastruntime.
+        $params = array('modulename' => 'assign', 'instance' => $assign2->get_instance()->id);
+        $event2 = $DB->get_record('event', $params);
+        $this->assertNotEmpty($event2);
+        $this->assertSame('This one should be re-created', $event2->description);
+    }
 }