Rails，Heroku：缺少模板应用程序/ not_found

Question

看来我的Rails 5应用程序（仅在生产中 - 在Heroku上）导致application/not_found缺少模板错误。此错误不会导致应用程序崩溃。

#<ActionView::MissingTemplate: Missing template application/not_found with {:locale=>[:en], :formats=>[nil], :variants=>[], :handlers=>[:raw, :erb, :html, :builder, :ruby, :coffee, :haml, :jbuilder]}. Searched in: 
   * "/app/app/views" 
   * "/app/vendor/bundle/ruby/2.3.0/gems/devise-authy-1.8.1/app/views" 
   * "/app/vendor/bundle/ruby/2.3.0/gems/devise_invitable-1.7.2/app/views" 
   * "/app/vendor/bundle/ruby/2.3.0/bundler/gems/devise-71fc5b351a8e/app/views" 
   * "/app/vendor/bundle/ruby/2.3.0/gems/kaminari-core-1.0.1/app/views" 
 > 

我将*path发送到application#not_found以捕获拼写错误的请求。

在ApplicationController：

rescue_from (ActiveRecord::RecordNotFound) { |exception| handle_exception(exception, 404) }
rescue_from (AbstractController::ActionNotFound) { |exception| handle_exception(exception, 404) }
rescue_from (ActionController::RoutingError) { |exception| handle_exception(exception, 404) }


def not_found
    raise ActionController::RoutingError.new(params[:path] || 'Not Found')
end

protected

def handle_exception ex, status
    render_error ex, status
    logger.error ex
end

def render_error ex, status
    @status_code = status
    respond_to do |format|
        if status == 404
            format.html { render template: 'errors/not_found', status: status }
        end
        format.all { render nothing: true, status: status }
    end
end

我认为通过指定render template: 'errors/not_found' Rails并且知道模板已经渲染。