# Bun Error Handling
> Learn how to handle errors in Bun's development server
- Skill: `jarle/bun-error-handling` (Agent Skill)
- Install (CLI): `npx skillmds@latest add jarle/bun-error-handling`
- Raw SKILL.md: https://api.skillmd.com/api/skills/jarle/bun-error-handling/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: jarle (https://skillmd.com/u/jarle)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/jarle/bun-error-handling
---
# Error Handling
> Learn how to handle errors in Bun's development server
To activate development mode, set `development: true`.
```ts title="server.ts" icon="https://mintcdn.com/bun-1dd33a4e/nIz6GtMH5K-dfXeV/icons/typescript.svg?fit=max&auto=format&n=nIz6GtMH5K-dfXeV&q=85&s=5d73d76daf7eb7b158469d8c30d349b0" theme={"theme":{"light":"github-light","dark":"dracula"}}
Bun.serve({
development: true, // [!code ++]
fetch(req) {
throw new Error("woops!");
},
});
```
In development mode, Bun will surface errors in-browser with a built-in error page.
### `error` callback
To handle server-side errors, implement an `error` handler. This function should return a `Response` to serve to the client when an error occurs. This response will supersede Bun's default error page in `development` mode.
```ts theme={"theme":{"light":"github-light","dark":"dracula"}}
Bun.serve({
fetch(req) {
throw new Error("woops!");
},
error(error) {
return new Response(`${error}\n${error.stack}`, {
headers: {
"Content-Type": "text/html",
},
});
},
});
```
[Learn more about debugging in Bun](/runtime/debugger)