diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 99f3b4c2cde2c..06ce165f76b96 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -1171,10 +1171,16 @@ def default_actions
           end
 
           def actions
+            if @except
+              available_actions - Array(@except).map(&:to_sym)
+            else
+              available_actions
+            end
+          end
+
+          def available_actions
             if @only
               Array(@only).map(&:to_sym)
-            elsif @except
-              default_actions - Array(@except).map(&:to_sym)
             else
               default_actions
             end
diff --git a/actionpack/test/controller/resources_test.rb b/actionpack/test/controller/resources_test.rb
index d336b96eff1d7..d2146f12a52bd 100644
--- a/actionpack/test/controller/resources_test.rb
+++ b/actionpack/test/controller/resources_test.rb
@@ -853,6 +853,28 @@ def test_singleton_resource_does_not_have_destroy_action
     end
   end
 
+  def test_resource_has_show_action_but_does_not_have_destroy_action
+    with_routing do |set|
+      set.draw do
+        resources :products, only: [:show, :destroy], except: :destroy
+      end
+
+      assert_resource_allowed_routes("products", {},                    { id: "1" }, :show, [:index, :new, :create, :edit, :update, :destroy])
+      assert_resource_allowed_routes("products", { format: "xml" },  { id: "1" }, :show, [:index, :new, :create, :edit, :update, :destroy])
+    end
+  end
+
+  def test_singleton_resource_has_show_action_but_does_not_have_destroy_action
+    with_routing do |set|
+      set.draw do
+        resource :account, only: [:show, :destroy], except: :destroy
+      end
+
+      assert_singleton_resource_allowed_routes("accounts", {},                    :show, [:new, :create, :edit, :update, :destroy])
+      assert_singleton_resource_allowed_routes("accounts", { format: "xml" },  :show, [:new, :create, :edit, :update, :destroy])
+    end
+  end
+
   def test_resource_has_only_create_action_and_named_route
     with_routing do |set|
       set.draw do