`captureException` not working in Next.js/Vercel Edge Runtime

[roch-numbered]

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/nextjs

SDK Version

7.81.1

Framework Version

Next.js 14.0.3 + React 18

Link to Sentry event

No response

SDK Setup

sentry.edge.config.ts

Sentry.init({
  dsn: SENTRY_DSN,

  // Adjust this value in production, or use tracesSampler for greater control
  tracesSampleRate: 1,

  // Setting this option to true will print useful information to the console while you're setting up Sentry.
  debug: false,
});

sentry.server.config.ts

Sentry.init({
  dsn: SENTRY_DSN,

  // Adjust this value in production, or use tracesSampler for greater control
  tracesSampleRate: 1,

  // Setting this option to true will print useful information to the console while you're setting up Sentry.
  debug: false,
});

Steps to Reproduce

1. On an Edge Runtime that responses with a ReadableStream.
2. Call captureException() after a promise.

Expected Result

Exceptions should be captured whatever the environment and the response type.

Actual Result

The exception is never captured to Sentry's dashboard.

---

When using Data Streaming from Next.js and Vercel in an Edge Runtime, it seems impossible to capture anything to Sentry after a promise is called. This bug isn't reproducible in NodeJS Runtime.

You can find a reproduction with instructions on setup here: https://github.com/roch-numbered/nextjs-stream

[AbhiPrasad]

if you call Sentry.captureException(X) and then await Sentry.flush(2000), does the exception get captured?

[roch-numbered]

@AbhiPrasad it is yes!

How is this possible? I don't get what flush() call is actually doing 🤔

[AbhiPrasad]

yeah so this is because Vercel is just closing the process, it doesn't wait for Sentry to send it's events to Sentry. In the case of streaming, it starts streaming the result, but stops execution of everything else.

flush just blocks the main thread until all the events have been sent to ensure everything is sent correctly.

@lforst I thought we flush by default though - is streaming scenario accounted for?

[roch-numbered]

Ok I think I get it, thanks @AbhiPrasad
I'll let you close the issue if you want to, my problem is fixed now 👍