diff --git a/core/modules/user/src/Plugin/LanguageNegotiation/LanguageNegotiationUserAdmin.php b/core/modules/user/src/Plugin/LanguageNegotiation/LanguageNegotiationUserAdmin.php
index c00509f..0b100ac 100644
--- a/core/modules/user/src/Plugin/LanguageNegotiation/LanguageNegotiationUserAdmin.php
+++ b/core/modules/user/src/Plugin/LanguageNegotiation/LanguageNegotiationUserAdmin.php
@@ -13,6 +13,7 @@
 use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
 use Symfony\Component\Routing\Exception\ResourceNotFoundException;
 use Symfony\Component\Routing\Matcher\UrlMatcherInterface;
+use Symfony\Component\Routing\Exception\MethodNotAllowedException;
 
 /**
  * Identifies admin language from the user preferences.
@@ -139,6 +140,9 @@ protected function isAdminPath(Request $request) {
         catch (AccessDeniedHttpException $e) {
           return FALSE;
         }
+        catch (MethodNotAllowedException $e) {
+          return FALSE;
+        }
         $route_object = $attributes[RouteObjectInterface::ROUTE_OBJECT];
       }
       $result = $this->adminContext->isAdminRoute($route_object);