From dec3e31ae5bd15840ec3847d1304cbd78c6d1f6a Mon Sep 17 00:00:00 2001
From: Charly Gomez <charly.gomez1310@gmail.com>
Date: Thu, 17 Sep 2026 14:51:44 +0200
Subject: [PATCH] fix(nextjs): Resolve Next.js version relative to the SDK when
 cwd differs

Next.js version detection only resolved `next/package.json` from `process.cwd()`.
When the process starts outside the Next.js project root (custom servers, monorepos),
detection returned undefined and `withSentryConfig` fell back to the Next 14 config
shape, silently dropping `serverExternalPackages` on Next 15+.

Fall back to resolving from the SDK's own location, where `next` is reachable as a
peer dependency.

Fixes #24461
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
---
 packages/nextjs/src/config/util.ts       | 21 +++++++++++++++++----
 packages/nextjs/test/config/util.test.ts | 20 +++++++++++++++++++-
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/packages/nextjs/src/config/util.ts b/packages/nextjs/src/config/util.ts
index 4ec25dbf0e94..5f0990ac6829 100644
--- a/packages/nextjs/src/config/util.ts
+++ b/packages/nextjs/src/config/util.ts
@@ -22,12 +22,25 @@ export function getNextjsVersion(): string | undefined {
   return undefined;
 }
 
+// Anchored at this package so `next` (a peer dependency) still resolves when the process cwd is not
+// the Next.js project root, e.g. custom servers or monorepos started from the repo root.
+let sdkRequire: NodeJS.Require;
+/*! rollup-include-cjs-only */
+sdkRequire = createRequire(__filename);
+/*! rollup-include-cjs-only-end */
+/*! rollup-include-esm-only */
+sdkRequire = createRequire(import.meta.url);
+/*! rollup-include-esm-only-end */
+
 function resolveNextjsPackageJson(): string | undefined {
-  try {
-    return createRequire(`${process.cwd()}/`).resolve('next/package.json');
-  } catch {
-    return undefined;
+  for (const nodeRequire of [createRequire(`${process.cwd()}/`), sdkRequire]) {
+    try {
+      return nodeRequire.resolve('next/package.json');
+    } catch {
+      // try next
+    }
   }
+  return undefined;
 }
 
 /**
diff --git a/packages/nextjs/test/config/util.test.ts b/packages/nextjs/test/config/util.test.ts
index 01b5e59af28e..62632d4bc7aa 100644
--- a/packages/nextjs/test/config/util.test.ts
+++ b/packages/nextjs/test/config/util.test.ts
@@ -1,7 +1,25 @@
-import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import * as os from 'os';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import * as util from '../../src/config/util';
 
 describe('util', () => {
+  describe('getNextjsVersion', () => {
+    afterEach(() => {
+      vi.restoreAllMocks();
+    });
+
+    it('returns the installed Next.js version', () => {
+      expect(util.getNextjsVersion()).toMatch(/^\d+\.\d+\.\d+/);
+    });
+
+    it('returns the installed Next.js version when cwd is not the project root', () => {
+      const expected = util.getNextjsVersion();
+      vi.spyOn(process, 'cwd').mockReturnValue(os.tmpdir());
+
+      expect(util.getNextjsVersion()).toBe(expected);
+    });
+  });
+
   describe('supportsProductionCompileHook', () => {
     describe('supported versions', () => {
       it('returns true for Next.js 15.4.1', () => {