Bun troubleshooting: locating and fixing high-frequency failures
The most common production failures for Bun and their root-cause fixes.
Quick answer
How does Bun differ from the Node API?
Bun fs and a few APIs differ from Node. Pin the Bun version in CI to avoid local-works-but-CI-breaks surprises.
Machine-readable page data: /data/bun-troubleshooting.json
In-depth analysis
Bun unifies runtime, package manager, and bundler into one toolchain, beating Node on startup and install speed. It pairs especially well with AI coding workflows. Troubleshoot by three layers — build, deploy, runtime — diagnose by symptom, never blind-trial.
// Local server + script runner with Bun (zero extra deps)
Bun.serve({ port: 3000, fetch: () => new Response('hi') });
// Install: bun install Run: bun run dev Build: bun build ./src/index.tsBun Troubleshooting · Key takeaways
- Build, deploy, or runtime layer identified
- Relevant logs and status codes captured
- Fix verified and reproducible
- Fix notes recorded for reuse
FAQ & pitfalls
Why does my existing project break when I run it on Bun?
Native modules may be missing or APIs differ. Bootstrap new projects with bun first, then migrate legacy projects gradually and fill in types.
How do I cache Bun build artifacts at the edge?
Artifacts use hash filenames with immutable long cache. Bun itself does not participate in runtime — static delivery is handled by the edge.
Explore the hub
See all 5 guides in BunSame category as this article, sorted across the codebase.
Bun architecture: layered patterns for high-concurrency edge apps
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Bun best practices: engineering conventions for production
Field-tested Bun practices from production, avoiding the common anti-patterns.
Bun deployment guide: zero-ops edge publishing with Cloudflare Pages
Git-driven Bun deployment in practice: commit to build, atomic publish to every edge node.
Bun performance tuning: push first paint and edge response to the limit
Around Bun's real bottlenecks, an actionable LCP / INP / CLS checklist.
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What readers are asking
Questions that keep coming back in reader feedback, already answered.
- 01
Why does the same project error out when I run it with Bun?
Native modules are missing, or some Node APIs behave differently under Bun. Pin the Bun version in CI; migrate older projects gradually and initialise new ones with Bun directly.
See the full guide → - 02
Why is my Astro component's interactivity not working?
Components ship as zero-JS HTML by default, so an interactive one needs a client:* directive (client:load, client:visible, …). Without it the script is never bundled into the page.
See the full guide → - 03
Why is my custom Tailwind v4 brand colour not applied?
Colours must be declared in @theme (for example --color-brand). A missing @tailwindcss/vite plugin, or a leftover v3 config, makes bg-brand silently render nothing.
See the full guide →