diff --git a/core/lib/Drupal/Core/RouteProcessor/RouteProcessorCurrent.php b/core/lib/Drupal/Core/RouteProcessor/RouteProcessorCurrent.php
index 3fc61b9..efafdcc 100644
--- a/core/lib/Drupal/Core/RouteProcessor/RouteProcessorCurrent.php
+++ b/core/lib/Drupal/Core/RouteProcessor/RouteProcessorCurrent.php
@@ -40,7 +40,6 @@ public function processOutbound($route_name, Route $route, array &$parameters, C
     if ($route_name === '<current>') {
       if ($current_route = $this->routeMatch->getRouteObject()) {
         $requirements = $current_route->getRequirements();
-        unset($requirements['_format']);
         unset($requirements['_method']);
         unset($requirements['_schema']);
         $route->setRequirements($requirements);