diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 28e2f1ef05f..8aabe15767f 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -3948,5 +3948,16 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2019111804.08);
     }
 
+    if ($oldversion < 2019111805.09) {
+        // Delete orphaned course_modules_completion rows; these were not deleted properly
+        // by remove_course_contents function.
+        $DB->delete_records_subquery('course_modules_completion', 'id', 'id',
+               "SELECT cmc.id
+                  FROM {course_modules_completion} cmc
+             LEFT JOIN {course_modules} cm ON cm.id = cmc.coursemoduleid
+                 WHERE cm.id IS NULL");
+        upgrade_main_savepoint(true, 2019111805.09);
+    }
+
     return true;
 }
diff --git a/lib/dml/moodle_database.php b/lib/dml/moodle_database.php
index c0b574ddf56..d182cf117d4 100644
--- a/lib/dml/moodle_database.php
+++ b/lib/dml/moodle_database.php
@@ -1970,7 +1970,7 @@ abstract class moodle_database {
      * @param string $subquery Subquery that will return values of the field to delete
      * @param array $params Parameters for subquery
      * @throws dml_exception If there is any error
-     * @since Moodle 3.10
+     * @since Moodle 3.8.6
      */
     public function delete_records_subquery(string $table, string $field, string $alias,
             string $subquery, array $params = []): void {
diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index d4c5e583373..36c4a45ee41 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -5256,6 +5256,7 @@ function remove_course_contents($courseid, $showfeedback = true, array $options
                     if ($cm->id) {
                         // Delete cm and its context - orphaned contexts are purged in cron in case of any race condition.
                         context_helper::delete_instance(CONTEXT_MODULE, $cm->id);
+                        $DB->delete_records('course_modules_completion', ['coursemoduleid' => $cm->id]);
                         $DB->delete_records('course_modules', array('id' => $cm->id));
                         rebuild_course_cache($cm->course, true);
                     }
diff --git a/version.php b/version.php
index 49781064d44..8dd5df77736 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2019111805.08;              // 20191118      = branching date YYYYMMDD - do not modify!
+$version  = 2019111805.09;              // 20191118      = branching date YYYYMMDD - do not modify!
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.
 $release  = '3.8.5+ (Build: 20201016)'; // Human-friendly version name