Raise a helpful error if config.frameworks is used

railties/lib/rails/configuration.rb

@@ -119,6 +119,13 @@ module Rails
       end
     end
 
+    def frameworks(*args)
+      raise "config.frameworks in no longer supported. See the generated" \
+            "config/boot.rb for steps on how to limit the frameworks that" \
+            "will be loaded"
+    end
+    alias frameworks= frameworks
+
     # Enable threaded mode. Allows concurrent requests to controller actions and
     # multiple database connections. Also disables automatic dependency loading
     # after boot, and disables reloading code on every request, as these are

railties/test/application/configuration_test.rb

@@ -100,5 +100,21 @@ module ApplicationTests
 
       assert !ActionController.autoload?(:RecordIdentifier)
     end
+
+    test "runtime error is raised if config.frameworks= is used" do
+      add_to_config "config.frameworks = []"
+
+      assert_raises RuntimeError do
+        require "#{app_path}/config/environment"
+      end
+    end
+
+    test "runtime error is raised if config.frameworks is used" do
+      add_to_config "config.frameworks -= []"
+
+      assert_raises RuntimeError do
+        require "#{app_path}/config/environment"
+      end
+    end
   end
 end