`Sentry.sentryHandle()` raises `TypeError: Body is unusable: Body has already been read` when node >= 20 (20.x, 22.x)

[chenqianhe]

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/sveltekit

SDK Version

8.42.0

Framework Version

"@sveltejs/kit": "^2.6.2", "svelte": "^4.1.2", "@sveltejs/adapter-vercel": "^5.5.0"

Link to Sentry event

https://learnie-ai.sentry.io/issues/6106002320/events/32c06c33715a481caeabbb2569eb7853/?project=4505632768262144

Reproduction Example/SDK Setup

On hooks.server.ts:

Sentry.init({
 dsn: "xxx",
 tracesSampleRate: 1.0,
 integrations: [Sentry.consoleIntegration(), Sentry.captureConsoleIntegration({ levels: ["error"] })],
 enabled: import.meta.env.MODE === "production",
});

export const handle = sequence(Sentry.sentryHandle(), mySelfHandle);

Steps to Reproduce

1. Use node 20.x or node 22.x (btw, no bugs on Node 18.x)
2. Enable Sentry
3. Send multiple requests to an interface at the same time

Expected Result

All requests are received and returned normally

Actual Result

A small number (one or two) of them return results normally, but the rest all have errors:

TypeError: Body is unusable: Body has already been read
 at consumeBody (node:internal/deps/undici/undici:5463:15)
 at _Request.json (node:internal/deps/undici/undici:5416:18)
 at POST (file:///var/task/vercel/path0/.svelte-kit/output/server/entries/endpoints/api/v1/quiz/freeform/_server.ts.js:20:32)
 at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
 at async render_endpoint (file:///var/task/vercel/path0/.svelte-kit/output/server/index.js:184:20)
 at async resolve2 (file:///var/task/vercel/path0/.svelte-kit/output/server/index.js:2721:22)
 at async sessionCookieInvalidationHandle (file:///var/task/vercel/path0/.svelte-kit/output/server/chunks/hooks.server.js:68:20)
 at async /var/task/vercel/path0/node_modules/@sentry/sveltekit/build/cjs/server/handle.js:140:21
 at async instrumentHandle (/var/task/vercel/path0/node_modules/@sentry/sveltekit/build/cjs/server/handle.js:128:27)
 at async respond (file:///var/task/vercel/path0/.svelte-kit/output/server/index.js:2615:22)

[chenqianhe]

1. I'm sure it's not from mySelfHandle, because I tried it and everything worked fine:

export const handle = sequence(mySelfHandle, mySelfHandle);

2. I'm sure it's a Sentry related error because everything works fine after I removed it:

export const handle = sequence(mySelfHandle);

3. I don't think it's an error caused by undici, because I checked the source code and found that the clone function in fetch provided by undici is indeed a so-called deep copy. (Node implemented fetch on undici after Node 20.x, different between Node 18.x, But I didn't find much difference in their behavior)

https://github.com/nodejs/undici/blob/9e6d34d6dcf47aed9da997550cba6f158983b20c/lib/web/fetch/request.js#L760

https://github.com/nodejs/undici/blob/9e6d34d6dcf47aed9da997550cba6f158983b20c/lib/web/fetch/body.js#L286

4. I also checked Sentry.sentryHandle() source code, but I really don't have any clues

[s1gr1d]

Hello, can you provide a small runnable reproduction example? This can be for example a GitHub repository with a small SvelteKit project that includes e.g. a button for the request and the Sentry setup. Thank you! :)

[chenqianhe]

Hello, can you provide a small runnable reproduction example? This can be for example a GitHub repository with a small SvelteKit project that includes e.g. a button for the request and the Sentry setup. Thank you! :)

https://github.com/chenqianhe/node-20-sentry-demo

https://node-20-sentry-demo.vercel.app/

I have to say, at the moment I can't reproduce this bug in either this minimal example or our real project.