diff --git a/metatag.module b/metatag.module
index d709130..529b6b9 100644
--- a/metatag.module
+++ b/metatag.module
@@ -192,8 +192,11 @@ function metatag_get_route_entity() {
   preg_match('/(entity\.)?(.*)\.add(_form)?/', $route_name, $route_name_matches);
   if (!empty($route_name_matches[2])) {
     $entity_type = $route_name_matches[2];
-    $definition = Drupal::entityTypeManager()->getDefinition($entity_type);
-    $type = $route_match->getRawParameter($definition->get('bundle_entity_type'));
+    $definition = Drupal::entityTypeManager()->getDefinition($entity_type, FALSE);
+    $type = NULL;
+    if ($definition) {
+      $type = $route_match->getRawParameter($definition->get('bundle_entity_type'));
+    }
 
     if (!empty($type)) {
       return \Drupal::entityTypeManager()