Error Handling

Error handlers run within the same context as routes and before filters which means you get all the power of those.

404 Not Found

error 404 do
  "This is a customized 404 page."
end

When a Kemal::Exceptions::NotFound exception is raised, or the response’s status code is 404, the error 404 handler is invoked:

You can customize the built-in error 404 handler.

Custom error handlers for status codes

Just like error 404 handler you can install custom error handlers for different status codes.

error 403 do
  "Access Forbidden!"
end

get "/" do |env|
  env.response.status_code = 403
end