Issue #2269453 by olli: Apc_fetch() expects a string or array of strings.

core/lib/Drupal/Core/Cache/ApcuBackend.php

@@ -243,8 +243,7 @@ public function deleteAll() {
    * {@inheritdoc}
    */
   public function garbageCollection() {
-    // Any call to apc_fetch() causes APC to expunge expired items.
-    apc_fetch('');
+    // APC performs garbage collection automatically.
   }
 
   /**