diff --git a/actionpack/lib/action_controller/metal.rb b/actionpack/lib/action_controller/metal.rb
index <HASH>..<HASH> 100644
--- a/actionpack/lib/action_controller/metal.rb
+++ b/actionpack/lib/action_controller/metal.rb
@@ -116,8 +116,6 @@ module ActionController
   class Metal < AbstractController::Base
     abstract!
 
-    attr_internal_writer :env
-
     def env
       @_request.env
     end
the request object manages `env`

remove the setter.  The request object manages the env hash, so any
mutations need to go through it