fix(nextjs): Don't capture suspense errors in server components (#12261)

Author: Luca Forstner

dev-packages/e2e-tests/test-applications/nextjs-15/app/suspense-error/page.tsx

@@ -0,0 +1,15 @@
+import * as Sentry from '@sentry/nextjs';
+import { use } from 'react';
+export const dynamic = 'force-dynamic';
+
+export default async function Page() {
+  try {
+    use(fetch('http://example.com/'));
+  } catch (e) {
+    Sentry.captureException(e); // This error should not be reported
+    await new Promise(resolve => setTimeout(resolve, 1000)); // Wait for any async event processors to run
+    await Sentry.flush();
+  }
+
+  return <p>test</p>;
+}

dev-packages/e2e-tests/test-applications/nextjs-15/tests/suspense-error.test.ts

@@ -0,0 +1,24 @@
+import { expect, test } from '@playwright/test';
+import { waitForError, waitForTransaction } from '@sentry-internal/event-proxy-server';
+
+test('should not capture serverside suspense errors', async ({ page }) => {
+  const pageServerComponentTransactionPromise = waitForTransaction('nextjs-15', async transactionEvent => {
+    return transactionEvent?.transaction === 'Page Server Component (/suspense-error)';
+  });
+
+  let errorEvent;
+  waitForError('nextjs-15', async transactionEvent => {
+    return transactionEvent?.transaction === 'Page Server Component (/suspense-error)';
+  }).then(event => {
+    errorEvent = event;
+  });
+
+  await page.goto(`/suspense-error`);
+
+  await page.waitForTimeout(5000);
+
+  const pageServerComponentTransaction = await pageServerComponentTransactionPromise;
+  expect(pageServerComponentTransaction).toBeDefined();
+
+  expect(errorEvent).toBeUndefined();
+});

packages/nextjs/src/server/index.ts

@@ -190,13 +190,23 @@ export function init(options: NodeOptions): void {
 
         const originalException = hint.originalException;
 
-        const isReactControlFlowError =
+        const isPostponeError =
           typeof originalException === 'object' &&
           originalException !== null &&
           '$$typeof' in originalException &&
           originalException.$$typeof === Symbol.for('react.postpone');
 
-        if (isReactControlFlowError) {
+        if (isPostponeError) {
+          // Postpone errors are used for partial-pre-rendering (PPR)
+          return null;
+        }
+
+        // We don't want to capture suspense errors as they are simply used by React/Next.js for control flow
+        const exceptionMessage = event.exception?.values?.[0]?.value;
+        if (
+          exceptionMessage?.includes('Suspense Exception: This is not a real error!') ||
+          exceptionMessage?.includes('Suspense Exception: This is not a real error, and should not leak')
+        ) {
           return null;
         }