fix(nextjs): Don't capture not-found and redirect errors in generation functions

dev-packages/e2e-tests/test-applications/nextjs-14/app/generation-functions/with-notfound/page.tsx

@@ -0,0 +1,11 @@
+import { notFound } from 'next/navigation';
+
+export const dynamic = 'force-dynamic';
+
+export default function PageWithRedirect() {
+  return <p>Hello World!</p>;
+}
+
+export async function generateMetadata() {
+  notFound();
+}

dev-packages/e2e-tests/test-applications/nextjs-14/app/generation-functions/with-redirect/page.tsx

@@ -0,0 +1,11 @@
+import { redirect } from 'next/navigation';
+
+export const dynamic = 'force-dynamic';
+
+export default function PageWithRedirect() {
+  return <p>Hello World!</p>;
+}
+
+export async function generateMetadata() {
+  redirect('/');
+}

dev-packages/e2e-tests/test-applications/nextjs-14/app/page.tsx

@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>Home</p>;
+}

dev-packages/e2e-tests/test-applications/nextjs-14/tests/generation-functions.test.ts

@@ -77,3 +77,37 @@ test('Should send a transaction and an error event for a faulty generateViewport
   expect(await transactionPromise).toBeDefined();
   expect(await errorEventPromise).toBeDefined();
 });
+
+test('Should send a transaction event with correct status for a generateMetadata() function invokation with redirect()', async ({
+  page,
+}) => {
+  const testTitle = 'redirect-foobar';
+
+  const transactionPromise = waitForTransaction('nextjs-14', async transactionEvent => {
+    return (
+      transactionEvent?.transaction === 'Page.generateMetadata (/generation-functions/with-redirect)' &&
+      transactionEvent.contexts?.trace?.data?.['searchParams']?.['metadataTitle'] === testTitle
+    );
+  });
+
+  await page.goto(`/generation-functions/with-redirect?metadataTitle=${testTitle}`);
+
+  expect((await transactionPromise).contexts?.trace?.status).toBe('ok');
+});
+
+test('Should send a transaction event with correct status for a generateMetadata() function invokation with notfound()', async ({
+  page,
+}) => {
+  const testTitle = 'notfound-foobar';
+
+  const transactionPromise = waitForTransaction('nextjs-14', async transactionEvent => {
+    return (
+      transactionEvent?.transaction === 'Page.generateMetadata (/generation-functions/with-notfound)' &&
+      transactionEvent.contexts?.trace?.data?.['searchParams']?.['metadataTitle'] === testTitle
+    );
+  });
+
+  await page.goto(`/generation-functions/with-notfound?metadataTitle=${testTitle}`);
+
+  expect((await transactionPromise).contexts?.trace?.status).toBe('not_found');
+});

packages/nextjs/src/common/wrapGenerationFunctionWithSentry.ts

@@ -6,12 +6,13 @@ import {
   getCurrentScope,
   handleCallbackErrors,
   runWithAsyncContext,
-  startSpan,
+  startSpanManual,
 } from '@sentry/core';
 import type { WebFetchHeaders } from '@sentry/types';
 import { winterCGHeadersToDict } from '@sentry/utils';
 
 import type { GenerationFunctionContext } from '../common/types';
+import { isNotFoundNavigationError, isRedirectNavigationError } from './nextNavigationErrorUtils';
 import { commonObjectToPropagationContext } from './utils/commonObjectTracing';
 
 /**
@@ -61,7 +62,7 @@ export function wrapGenerationFunctionWithSentry<F extends (...args: any[]) => a
           transactionContext.parentSpanId = commonSpanId;
         }
 
-        return startSpan(
+        return startSpanManual(
           {
             op: 'function.nextjs',
             name: `${componentType}.${generationFunctionIdentifier} (${componentRoute})`,
@@ -76,18 +77,31 @@ export function wrapGenerationFunctionWithSentry<F extends (...args: any[]) => a
               },
             },
           },
-          () => {
+          span => {
             return handleCallbackErrors(
               () => originalFunction.apply(thisArg, args),
-              err =>
-                captureException(err, {
-                  mechanism: {
-                    handled: false,
-                    data: {
-                      function: 'wrapGenerationFunctionWithSentry',
+              err => {
+                if (isNotFoundNavigationError(err)) {
+                  // We don't want to report "not-found"s
+                  span?.setStatus('not_found');
+                } else if (isRedirectNavigationError(err)) {
+                  // We don't want to report redirects
+                  span?.setStatus('ok');
+                } else {
+                  span?.setStatus('internal_error');
+                  captureException(err, {
+                    mechanism: {
+                      handled: false,
+                      data: {
+                        function: 'wrapGenerationFunctionWithSentry',
+                      },
                     },
-                  },
-                }),
+                  });
+                }
+              },
+              () => {
+                span?.end();
+              },
             );
           },
         );