Added a note about how to enable http_method_override for caching kernels

book/http_cache.rst

@@ -163,6 +163,23 @@ kernel::
 The caching kernel will immediately act as a reverse proxy - caching responses
 from your application and returning them to the client.
 
+..caution::
+
+    By default, the caching kernel ignores the ``framework.http_method_override``
+    option, which could lead to errors when using ``PUT``, ``DELETE`` and ``PURGE``
+    methods in HTTP requests.
+
+    Invoke the ``enableHttpMethodParameterOverride()`` method before creating the
+    ``Request`` object in order to take this option into account::
+
+        // web/app.php
+        // ...
+        $kernel = new AppCache($kernel);
+
+        Request::enableHttpMethodParameterOverride(); // <-- add this line
+        $request = Request::createFromGlobals();
+        // ...
+
 .. tip::
 
     The cache kernel has a special ``getLog()`` method that returns a string

reference/configuration/framework.rst

@@ -77,9 +77,12 @@ http_method_override
 This determines whether the ``_method`` request parameter is used as the intended
 HTTP method on POST requests. If enabled, the
 :method:`Request::enableHttpMethodParameterOverride <Symfony\\Component\\HttpFoundation\\Request::enableHttpMethodParameterOverride>`
-method gets called automatically. It becomes the service container parameter
-named ``kernel.http_method_override``. For more information, see
-:doc:`/cookbook/routing/method_parameters`.
+method gets called automatically, unless the application uses a caching kernel,
+where you need to invoke that method manually (see :ref:`symfony2-reverse-proxy`
+for details).
+
+It becomes the service container parameter named ``kernel.http_method_override``.
+For more information, see :doc:`/cookbook/routing/method_parameters`.
 
 ide
 ~~~