diff --git a/comment_notify.inc b/comment_notify.inc
index 105f8e66a7e5b12bb55fbb418618376f5560f5fc..65e01e9b90f7d68e32ae3faf16cf53f7242ecfba 100644
--- a/comment_notify.inc
+++ b/comment_notify.inc
@@ -27,7 +27,7 @@ function comment_notify_get_user_notification_setting($uid) {
       $users[0] = comment_notify_get_default_notification_setting();
     }
     else {
-      $setting = db_select('comment_notify_user_settings', 'cnus')
+      $setting = \Drupal::database()->select('comment_notify_user_settings', 'cnus')
         ->fields('cnus')
         ->condition('uid', $uid)
         ->execute()
@@ -64,7 +64,7 @@ function comment_notify_get_default_notification_setting() {
  *   TRUE if the preferences were removed correctly, FALSE if weren't removed.
  */
 function comment_notify_delete_user_notification_setting($uid) {
-  return (bool) db_delete('comment_notify_user_settings')
+  return (bool) \Drupal::database()->delete('comment_notify_user_settings')
     ->condition('uid', $uid)
     ->execute();
 }
@@ -131,11 +131,11 @@ function comment_notify_set_user_notification_setting($uid, $entity_notification
     $fields['comment_notify'] = $comment_notification;
   }
   if (comment_notify_get_user_notification_setting($uid)) {
-    $query = db_update('comment_notify_user_settings');
+    $query = \Drupal::database()->update('comment_notify_user_settings');
     $query->condition('uid', $uid);
   }
   else {
-    $query = db_insert('comment_notify_user_settings');
+    $query = \Drupal::database()->insert('comment_notify_user_settings');
   }
   return (bool) $query
     ->fields($fields)
@@ -159,7 +159,7 @@ function comment_notify_set_user_notification_setting($uid, $entity_notification
  */
 function comment_notify_add_notification($cid, $notify, $notify_hash, $notified) {
   // Check if comment already exist.
-  $results = db_select('comment_notify', 'cn')
+  $results = \Drupal::database()->select('comment_notify', 'cn')
     ->fields('cn', ['cid'])
     ->condition('cn.cid', $cid)
     ->execute()
@@ -167,7 +167,7 @@ function comment_notify_add_notification($cid, $notify, $notify_hash, $notified)
 
   // Update comment if exist.
   if ($results) {
-    return (bool) db_update('comment_notify')
+    return (bool) \Drupal::database()->update('comment_notify')
       ->fields([
         'notify' => $notify === NULL ? 0 : $notify,
         'notify_hash' => $notify_hash,
@@ -179,7 +179,7 @@ function comment_notify_add_notification($cid, $notify, $notify_hash, $notified)
 
   // Create new entry.
   else {
-    return (bool) db_insert('comment_notify')
+    return (bool) \Drupal::database()->insert('comment_notify')
       ->fields([
         'cid' => $cid,
         'notify' => $notify === NULL ? 0 : $notify,
@@ -200,7 +200,7 @@ function comment_notify_add_notification($cid, $notify, $notify_hash, $notified)
  *   TRUE if all the notifications were removed correctly.
  */
 function comment_notify_remove_all_notifications($cid) {
-  return (bool) db_delete('comment_notify')
+  return (bool) \Drupal::database()->delete('comment_notify')
     ->condition('cid', $cid)
     ->execute();
 }
@@ -217,7 +217,7 @@ function comment_notify_remove_all_notifications($cid) {
  *   TRUE if the notification was updated correctly.
  */
 function comment_notify_update_notification($cid, $notify) {
-  return (bool) db_update('comment_notify')
+  return (bool) \Drupal::database()->update('comment_notify')
     ->fields([
       'notify' => $notify === NULL ? 0 : $notify,
     ])
@@ -235,7 +235,7 @@ function comment_notify_update_notification($cid, $notify) {
  *   Return the notification type.
  */
 function comment_notify_get_notification_type($cid) {
-  return db_select('comment_notify', 'cn')
+  return \Drupal::database()->select('comment_notify', 'cn')
     ->fields('cn', ['notify'])
     ->condition('cid', $cid)
     ->execute()
@@ -254,13 +254,13 @@ function comment_notify_get_notification_type($cid) {
  *   A list of comment entities.
  */
 function comment_notify_get_watchers($entity_id, $comment_type) {
-  $cids = db_query("SELECT c.cid FROM {comment_field_data} c INNER JOIN {comment_notify} cn ON c.cid = cn.cid LEFT JOIN {users_field_data} u ON c.uid = u.uid WHERE c.entity_id = :entity_id AND c.comment_type = :comment_type AND c.status = :status AND cn.notify <> :notify AND (u.uid = 0 OR u.status = 1)", [
+  $cids = \Drupal::database()->query("SELECT c.cid FROM {comment_field_data} c INNER JOIN {comment_notify} cn ON c.cid = cn.cid LEFT JOIN {users_field_data} u ON c.uid = u.uid WHERE c.entity_id = :entity_id AND c.comment_type = :comment_type AND c.status = :status AND cn.notify <> :notify AND (u.uid = 0 OR u.status = 1)", [
     ':entity_id' => $entity_id,
     ':comment_type' => $comment_type,
     ':status' => CommentInterface::PUBLISHED,
     ':notify' => COMMENT_NOTIFY_DISABLED,
   ])->fetchCol();
-  return \Drupal::entityManager()->getStorage('comment')->loadMultiple($cids);
+  return \Drupal::entityTypeManager()->getStorage('comment')->loadMultiple($cids);
 }
 
 /**
@@ -277,7 +277,7 @@ function comment_notify_mark_comment_as_notified($comment) {
   $comment->notified = 1;
 
   // Next, store this fact in the DB as well.
-  return (bool) db_update('comment_notify')
+  return (bool) \Drupal::database()->update('comment_notify')
     ->fields([
       'notified' => 1,
     ])
@@ -312,7 +312,7 @@ function comment_notify_unsubscribe_by_email($mail) {
     return FALSE;
   }
 
-  $update_query = db_update('comment_notify');
+  $update_query = \Drupal::database()->update('comment_notify');
   $update_query->fields(['notify' => 0]);
   $update_query->condition('cid', $comment_query->execute(), 'IN');
 
@@ -331,7 +331,7 @@ function comment_notify_unsubscribe_by_email($mail) {
  *   Returns TRUE if the comment was unsubscribed correctly, FALSE otherwise.
  */
 function comment_notify_unsubscribe_by_hash($hash) {
-  $query = db_select('comment_notify', 'cn');
+  $query = \Drupal::database()->select('comment_notify', 'cn');
   $query->join('comment_field_data', 'cf', 'cn.cid = cf.cid');
   $query->condition('cn.notify_hash', $hash)
     ->condition('cn.notify', COMMENT_NOTIFY_DISABLED, '!=')
@@ -347,7 +347,7 @@ function comment_notify_unsubscribe_by_hash($hash) {
   // If this notification is at the entity level and the commenter has a Drupal
   // account, delete all notifications for this entity.
   if (COMMENT_NOTIFY_ENTITY == $notification->notify && $notification->uid) {
-    $result = db_query("SELECT cid FROM {comment_field_data} WHERE entity_id = :entity_id AND entity_type = :entity_type AND uid = :uid", [
+    $result = \Drupal::database()->query("SELECT cid FROM {comment_field_data} WHERE entity_id = :entity_id AND entity_type = :entity_type AND uid = :uid", [
       ':entity_id' => $notification->entity_id,
       ':entity_type' => $notification->entity_type,
       ':uid' => $notification->uid,
@@ -355,7 +355,7 @@ function comment_notify_unsubscribe_by_hash($hash) {
     $cids = $result->fetchCol();
 
     // Update all comment notifications to be disabled.
-    return (bool) db_update('comment_notify')
+    return (bool) \Drupal::database()->update('comment_notify')
       ->fields([
         'notify' => 0,
       ])
@@ -364,7 +364,7 @@ function comment_notify_unsubscribe_by_hash($hash) {
   }
   else {
     // Update this notification to be disabled.
-    return (bool) db_update('comment_notify')
+    return (bool) \Drupal::database()->update('comment_notify')
       ->fields([
         'notify' => 0,
       ])
diff --git a/comment_notify.module b/comment_notify.module
index 5f8ca983396a34ef91b92d11c4c4bfd1c4e0f3ea..cdb8623fae27ce6466a72ee091175b5728dd6196 100644
--- a/comment_notify.module
+++ b/comment_notify.module
@@ -231,7 +231,7 @@ function comment_notify_form_user_form_alter(&$form, FormStateInterface &$form_s
   // entities.
   $bundles = FALSE;
   foreach (_comment_notify_get_comment_enabled_bundles() as $entity_type => $bundle) {
-    if (\Drupal::entityManager()->getAccessControlHandler($entity_type)->createAccess($bundle)) {
+    if (\Drupal::entityTypeManager()->getAccessControlHandler($entity_type)->createAccess($bundle)) {
       $bundles = TRUE;
       break;
     }
@@ -332,7 +332,7 @@ function comment_notify_remove_user_settings($uid) {
  */
 function comment_notify_comment_load($comments) {
   // Load some comment_notify specific information into the comment object.
-  $query = db_select('comment_notify', 'cn');
+  $query = \Drupal::database()->select('comment_notify', 'cn');
   $query->join('comment_field_data', 'c', 'c.cid = cn.cid');
   $query->leftJoin('users_field_data', 'u', 'c.uid = u.uid');
   $query->condition('c.cid', array_keys($comments), 'IN');
@@ -379,7 +379,7 @@ function _comment_notify_mailalert(CommentInterface $comment) {
   }
 
   /** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
-  $entity = \Drupal::entityManager()->getStorage($entity_type)->load($entity_id);
+  $entity = \Drupal::entityTypeManager()->getStorage($entity_type)->load($entity_id);
 
   // No mails if this is not an enabled content type.
   $enabled_types = $config->get('bundle_types');
@@ -464,7 +464,7 @@ function _comment_notify_mailalert(CommentInterface $comment) {
     // Trim the trailing / off the thread, if present.
     $alert_thread = rtrim((string) $alert->getThread(), '/');
 
-    $relevant_thread = Unicode::substr($thread, 0, Unicode::strlen($alert_thread));
+    $relevant_thread = mb_substr($thread, 0, mb_strlen($alert_thread));
     if ($alert->notify == COMMENT_NOTIFY_COMMENT && strcmp($relevant_thread, $alert_thread) != 0) {
       continue;
     }