core/lib/Drupal/Core/Routing/MethodFilter.php | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/core/lib/Drupal/Core/Routing/MethodFilter.php b/core/lib/Drupal/Core/Routing/MethodFilter.php
index 6d3c2e0..80812d4 100644
--- a/core/lib/Drupal/Core/Routing/MethodFilter.php
+++ b/core/lib/Drupal/Core/Routing/MethodFilter.php
@@ -27,8 +27,15 @@ public function filter(RouteCollection $collection, Request $request) {
 
     foreach ($collection as $name => $route) {
       $supported_methods = $route->getMethods();
-      $all_supported_methods = array_merge($supported_methods, $all_supported_methods);
-      if (!in_array($method, $supported_methods)) {
+
+      // A route not restricted to specific methods allows any method. If this
+      // is the case, we'll also have at least one route left in the collection,
+      // hence we don't need to calculate the set of all supported methods.
+      if (empty($supported_methods)) {
+        continue;
+      }
+      elseif (!in_array($method, $supported_methods)) {
+        $all_supported_methods = array_merge($supported_methods, $all_supported_methods);
         $collection->remove($name);
       }
     }