Error Handling

To activate development mode, set development: true.

server.ts

Bun.serve({
  development: true, 
  fetch(req) {
    throw new Error("woops!");
  },
});

In development mode, Bun surfaces errors in-browser with a built-in error page.

`error` callback

To handle server-side errors, implement an error handler. Return a Response to serve to the client when an error occurs. In development mode, this response replaces Bun’s default error page.

Bun.serve({
  fetch(req) {
    throw new Error("woops!");
  },
  error(error) {
    return new Response(`<pre>${error}\n${error.stack}</pre>`, {
      headers: {
        "Content-Type": "text/html",
      },
    });
  },
});

Learn more about debugging in Bun

TLS

Metrics

Get Started

Core Runtime

File & Module System

HTTP server

Networking

Data & Storage

Concurrency

Process & System

Interop & Tooling

Utilities

Standards & Compatibility

Contributing

Error Handling

`error` callback

​error callback

`error` callback