Bun fails to build @sentry/bun in cjs

[aminya]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/bun

SDK Version

10.10.0

Framework Version

Bun 1.2.21

Link to Sentry event

No response

Reproduction Example/SDK Setup

Bun fails to build @sentry/bun in cjs format with the error TypeError: Expected CommonJS module to have a function wrapper. If you weren't messing around with Bun's internals, this is a bug in Bun

Steps to Reproduce

1. Create src/index.ts with the following after installing @sentry/bun

import * as Sentry from '@sentry/bun'

2. Bundle

bun build ./src/index.ts --outdir dist --format cjs --target bun --sourcemap

3. Try to run run the bundle

bun ./dist/index.js

Expected Result

Should run

Actual Result

bun ./dist/index.js
 6 |     "use strict";
 7 | 
 8 |     //
 9 |     if (entry.instantiate)
10 |         return entry.instantiate;
11 |     var instantiatePromise = (async () => {
                                               ^
TypeError: Expected CommonJS module to have a function wrapper. If you weren't messing around with Bun's internals, this is a bug in Bun

Bun v1.2.21 (macOS arm64)

Additional Context

Workaround: Add --external @sentry/node to fix the issue.

_{Tip: React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.}

[linear]

JS-936 Bun fails to build @sentry/bun in cjs

[tusharrrr1]

. Mark @sentry/bun as external during build

You already found the workaround, this is the safest fix until upstream changes land:

Build in ESM format (preferred with Bun)

Since Bun is primarily an ESM runtime, skip CJS bundling

Fallback: use @sentry/node instead of @sentry/bun

If you only need core Sentry features and don’t rely on Bun-specific integrations, switch import:

Allow me to work on this can fix this

[mydea]

. Mark @sentry/bun as external during build

You already found the workaround, this is the safest fix until upstream changes land:

Build in ESM format (preferred with Bun)

Since Bun is primarily an ESM runtime, skip CJS bundling

Fallback: use @sentry/node instead of @sentry/bun

If you only need core Sentry features and don’t rely on Bun-specific integrations, switch import:

Allow me to work on this can fix this

Makes sense to me! Do you mean to fix this in bun, or is there something that needs to be fixed in the Sentry SDK (I can't really see what this would be, but to be sure)?

[tusharrrr1]

@mydea I believe both needs to be checked,
This appears to be either:
a compatibility issue with Bun’s CJS bundling, or
a missing export handling in @sentry/bun.

need to have a look into it.

[aminya]

Thanks for replies. The reason I use CJS bundling is to use the bytecode compilation for faster startup, which is only supported in the CJS mode. Yes, making the --external @sentry/node workaround does the job for now.

There's some activity here upstream. The bug is related to import.meta.
oven-sh/bun#22643