ActionController::BadRequest fix for specific locale

active_dispatch_fix.rb

module ActionDispatch::Routing::RouteSet::DispatcherFix
  def call env
    params = env[ActionDispatch::Routing::RouteSet::PARAMETERS_KEY]
    params.each do |key,value|
      next unless value.respond_to? :valid_encoding?
      next if value.valid_encoding?

      russian = value.force_encoding 'cp1251'
      params[key] = if russian.valid_encoding?
        russian.encode 'utf-8'
      else
        value.fix_encoding
      end
    end

    super
  end
end

ActionDispatch::Routing::RouteSet::Dispatcher.send :prepend, ActionDispatch::Routing::RouteSet::DispatcherFix