diff --git a/core/lib/Drupal/Core/Database/Connection.php b/core/lib/Drupal/Core/Database/Connection.php
index 34996b8a5..3f929eb83 100644
--- a/core/lib/Drupal/Core/Database/Connection.php
+++ b/core/lib/Drupal/Core/Database/Connection.php
@@ -1522,6 +1522,9 @@ public function escapeAlias($field) {
    *   The escaped string.
    */
   public function escapeLike($string) {
+    if (!isset($string)) {
+      return $string;
+    }
     return addcslashes($string, '\%_');
   }