Hide error details from client

One Paragraph Explainer

Exposing application error details to the client in production should be avoided due to the risk of exposing sensitive application details such as server file paths, third-party modules in use, and other internal workflows of the application which could be exploited by an attacker. Express comes with a built-in error handler, which takes care of any errors that might be encountered in the app. This default error-handling middleware function is added at the end of the middleware function stack. If you pass an error to next() and you do not handle it in a custom error handler, it will be handled by the built-in Express error handler; the error will be written to the client with the stack trace. This behaviour will be true when NODE_ENV is set to development, however when NODE_ENV is set to production, the stack trace is not written, only the HTTP response code.

Code example: Express error handler

  1. // production error handler
  2. // no stacktraces leaked to user
  3. app.use((err, req, res, next) => {
  4. res.status(err.status || 500);
  5. res.render('error', {
  6. message: err.message,
  7. error: {}
  8. });
  9. });

Additional resources

Express.js error handling documentation