diff --git a/core/lib/Drupal/Core/Cache/DatabaseBackend.php b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
index 7b91fe5..d98199e 100644
--- a/core/lib/Drupal/Core/Cache/DatabaseBackend.php
+++ b/core/lib/Drupal/Core/Cache/DatabaseBackend.php
@@ -251,7 +251,6 @@ protected function flattenTags(array $tags) {
    * Implements Drupal\Core\Cache\CacheBackendInterface::invalidateTags().
    */
   public function invalidateTags(array $tags) {
-    debug(debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS));
     foreach ($this->flattenTags($tags) as $tag) {
       unset(self::$tagCache[$tag]);
       $this->connection->merge('cache_tags')
diff --git a/core/lib/Drupal/Core/Cache/InstallBackend.php b/core/lib/Drupal/Core/Cache/InstallBackend.php
index be8cb8f..d66452c 100644
--- a/core/lib/Drupal/Core/Cache/InstallBackend.php
+++ b/core/lib/Drupal/Core/Cache/InstallBackend.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Core\Cache;
 
+use Drupal\Core\Database\Connection;
 use Exception;
 
 /**