Asynchronous errors aren't being reported in Next.js data-fetching methods on Vercel

[masonmcelvain]

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? If you use the CDN bundles, please specify the exact bundle (e.g. bundle.tracing.min.js) in your SDK setup.

@sentry/nextjs

SDK Version

7.44.2

Framework Version

12.2.3

Link to Sentry event

https://ifixit.sentry.io/issues/4031066228/?project=6475315&query=is%3Aunresolved&referrer=issue-stream

SDK Setup

Our source is public here. Debugging branch here, on the latest Sentry version.

Sentry.init({
   debug: true,
   dsn: SENTRY_DSN,
   sampleRate: 1.0,
   normalizeDepth: 5,
   initialScope: {
      tags: {
         'next.runtime': 'server',
      },
   },
   beforeSend(event, hint) {
      const ex = hint.originalException;
      if (ex instanceof Error) {
         // Happens when receiving a bad url that fails to decode
         if (ex.message.match(/URI malformed/)) {
            return null;
         }
      }
      return event;
   },
});

Steps to Reproduce

Similar to #6117 (which fixed this problem for synchronous errors), but reject a promise or throw an error in an async callback. When the project is run locally, the error is reported to Sentry. When deployed to Vercel, the error never appears in Sentry.

import { GetServerSideProps } from 'next';

const MyComponent = () => {
   return <h1>Hello World!</h1>;
};

export const getServerSideProps: GetServerSideProps = async (context) => {
   if (context.query.myParam === 'two') {
      // only throw conditionally so that this page actually builds
      Promise.reject(new Error("We don't like page two!"));
   }

   return { props: {} };
};

export default MyComponent;

Expected Result

An error like this one gets reported to Sentry.

Actual Result

No error is reported to Sentry. Here are the Vercel logs, if it's helpful:

Unhandled Promise Rejection 	{"errorType":"Runtime.UnhandledPromiseRejection","errorMessage":"Error: We don't like page two","reason":{"errorType":"Error","errorMessage":"We don't like page two","stack":["Error: We don't like page two","    at getServerSideProps (/var/task/frontend/.next/server/pages/myPage.js:27:24)","    at Object.renderToHTML (/var/task/node_modules/.pnpm/next@12.2.3_t7ss3ubh4wigfvyfclbvqff3gm/node_modules/next/dist/server/render.js:573:26)","    at processTicksAndRejections (node:internal/process/task_queues:96:5)","    at async doRender (/var/task/node_modules/.pnpm/next@12.2.3_t7ss3ubh4wigfvyfclbvqff3gm/node_modules/next/dist/server/base-server.js:915:38)","    at async cacheEntry.responseCache.get.isManualRevalidate.isManualRevalidate (/var/task/node_modules/.pnpm/next@12.2.3_t7ss3ubh4wigfvyfclbvqff3gm/node_modules/next/dist/server/base-server.js:1020:28)","    at async /var/task/node_modules/.pnpm/next@12.2.3_t7ss3ubh4wigfvyfclbvqff3gm/node_modules/next/dist/server/response-cache.js:69:36"]},"promise":{},"stack":["Runtime.UnhandledPromiseRejection: Error: We don't like page two","    at process.<anonymous> (file:///var/runtime/index.mjs:1188:17)","    at process.emit (node:events:525:35)","    at process.emit (node:domain:489:12)","    at emit (node:internal/process/promises:140:20)","    at processPromiseRejections (node:internal/process/promises:274:27)","    at processTicksAndRejections (node:internal/process/task_queues:97:32)"]}
Unknown application error occurred
Runtime.Unknown

CC @lforst

[lforst]

Hi, you set autoInstrumentServerFunctions: false in your next.config.js this will disable auto-instrumentation for data fetchers. If you want to have it instrumented with that option set to false you need to wrap it in wrapGetServerSidePropsWithSentry.

More info: https://docs.sentry.io/platforms/javascript/guides/nextjs/manual-setup/#opt-in-to-auto-instrumentation-on-specific-routes

[masonmcelvain]

I overlooked that config option, thank you for replying and pointing it out.

I tested dropping autoInstrumentServerFunctions: false but am still seeing the same results, where no error appears in Sentry despite an async error being thrown in getServerSideProps. As before, the error is reported when run locally, but does not get reported when deployed to Vercel.

I also tested using wrapGetServerSidePropsWithSentry without dropping the config option, and experienced the same results.

[lforst]

@masonmcelvain Hi, thanks for sharing your thoughts and experiments. I don't know if I can currently give a solution for this. It seems like Vercel is terminating the lambda before we're able to send the event out.

[masonmcelvain]

I don't know if I can currently give a solution for this.

My team and I haven't found a workaround either, but we'll share if we do.

It seems like Vercel is terminating the lambda before we're able to send the event out.

That's my hunch too, thanks for your take on it.

[github-actions]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you label it Status: Backlog or Status: In Progress, I will leave it alone ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀