reverted:
--- b/core/modules/page_cache/src/StackMiddleware/PageCache.php
+++ a/core/modules/page_cache/src/StackMiddleware/PageCache.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\page_cache\StackMiddleware;
 
-use Drupal\Component\Utility\UrlHelper;
 use Drupal\Component\Utility\UserAgent;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\CacheBackendInterface;
@@ -297,7 +296,7 @@
    */
   protected function getCacheId(Request $request) {
     $cid_parts = array(
+      $request->getUri(),
-      UrlHelper::encodePath($request->getUri()),
       $request->getRequestFormat(),
     );
     return implode(':', $cid_parts);