Catching unhandled promise rejections in an async Express route

My async route throws when a database call fails, and the whole server crashes instead of sending back an error response.

IntermediateRead 5 minDoing: about an hour7 steps

▶ Start

What you'll have at the end

One error-handling middleware that turns any async route's rejection into a matching HTTP status code, with every promise in the app either returned to it or given its own catch so none of them can crash the process.

Before you start

You need

An Express app already listening for requests, with at least one route that calls an async database or API function and no error-handling middleware defined yet.

Not covered

Wiring a process-wide crash-and-restart safety net for a background job or worker with no request waiting on it, which is a different problem once nobody is left to answer.

Leans on

7 steps

Where to go next

Why does your Node process die silently on a rejected promise?

when a rejection genuinely escapes every catch here and you want a process-wide log-and-restart safety net instead of a per-request fix.

Checked 25 Aug 2026

Part of the Express.js cookbook