Connect/Express Error and Therror handler

therror, error, express, connect, errorhandler, middleware
npm install therror-connect@2.2.1



therror-express implements a connect/express error handler middleware for Therror.ServerError

Logs all errors (by default) and replies with an error payload with only the error relevant information. Currently supports content negotiation for text/html, text/plain and application/json.

It's written in ES6, for node >= 4

npm version Build Status Coverage Status


 npm install --save therror-connect


const errorHandler = require('therror-connect');
const connect = require('connect');

let app = connect();

// The last one middleware added to your app
app.use(errorHandler()); // Some options can be provided. See below

Customize html with express

const express = require('express');
const app = express();

app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

  render: function(data, req, res, cb) {
    res.render(`/errors/${data.statusCode}`, data, cb);


let errorHandler = require('therror-connect');

errorHandler(options) Creates the middleware configured with the provided options object

options.log [Boolean] can be

  • true: logs the error using the error.log({req, res}) method. default
  • false: does nothing.

options.development [Boolean] can be

  • false: Dont add stack traces and development info to the payload. default
  • true: Add development info to the responses.

options.unexpectedClass [class] The Therror.ServerError class to instantiate when an unmanegeable error reaches the middleware. defaults to Therror.ServerError.InternalServerError

options.render Function to customize the sent html sent.

function render(data, req, res, cb) {
  // data.error: the error instance. 
  // error name. Eg: UnauthorizedError
  // data.message: error message. Eg: User 12 not authorized 
  // data.statusCode: associated statusCode to the message. Eg: 401
  // data.stack: looong string with the stacktrace (if options.development === true; else '')

  // req: Incoming http request
  // res: Outgoing http response. Warning! don't send the html, give it to the callback
  // cb: function(err, html) callback to call with the html

Peer Projects

  • therror: The Therror library, easy errors for nodejs
  • serr: Error serializer to Objects and Strings


Copyright 2016,2017 Telefónica I+D

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.