Update to Drupal 8.0.2. For more information, see https://www.drupal.org/drupal-8.0.2-release-notes

core/lib/Drupal/Component/FileCache/ApcuFileCacheBackend.php

@@ -16,21 +16,21 @@ class ApcuFileCacheBackend implements FileCacheBackendInterface {
    * {@inheritdoc}
    */
   public function fetch(array $cids) {
-    return apc_fetch($cids);
+    return apcu_fetch($cids);
   }
 
   /**
    * {@inheritdoc}
    */
   public function store($cid, $data) {
-    apc_store($cid, $data);
+    apcu_store($cid, $data);
   }
 
   /**
    * {@inheritdoc}
    */
   public function delete($cid) {
-    apc_delete($cid);
+    apcu_delete($cid);
   }
 
 }