next build crashes on Node 24.15+ and 25.7+ under Yarn PnP: require.extensions undefined in next-config-ts/require-hook.js

[kabo]

Link to the code that reproduces this issue

https://github.com/kabo/node-24.15-require-extensions-repro

To Reproduce

1. yarn create next-app@16.2.4 repro (any Next 16 project).
2. yarn set version 4.14.1
3. Ensure .yarnrc.yml has default nodeLinker (pnp) — i.e. don't set nodeLinker: node-modules.
4. Run with Node 24.15.0: yarn build.
5. Observes the stack trace below.

Current vs. Expected behavior

Expected: next build compiles and produces the .next/ output.

Actual: build exits with

file:///opt/atlassian/pipelines/agent/build/.yarn/__virtual__/next-virtual-51f158077e/6/root/.yarn/berry/cache/next-npm-16.2.4-a755a7c7e3-10.zip/node_modules/next/dist/build/next-config-ts/require-hook.js:35
const oldJSHook = require.extensions['.js'];
                                    ^
TypeError: Cannot read properties of undefined (reading '.js')
    at Object.<anonymous> (file:///.../next/dist/build/next-config-ts/require-hook.js:35:37)
    at loadCJSModule (node:internal/modules/esm/translators:185:3)
    at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:231:7)
    at ModuleJob.runSync (node:internal/modules/esm/module_job:404:39)
    at require (node:internal/modules/esm/translators:145:9)
    at Object.<anonymous> (file:///.../next/dist/build/next-config-ts/transpile-config.js:15:22)
    at loadCJSModule (node:internal/modules/esm/translators:185:3)
    at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:231:7)
    at ModuleJob.runSync (node:internal/modules/esm/module_job:404:39)
    at require (node:internal/modules/esm/translators:145:9)

Node.js v24.15.0

Crash happens regardless of whether the project uses next.config.ts or next.config.mjs, because transpile-config.js imports require-hook.js eagerly at top level.

Root cause (upstream)

This is a regression in Node.js v24.15.0: the require function passed to CJS modules loaded via the ESM loader no longer has .extensions defined when the module source comes through a custom loader (Yarn PnP's zip loader). Verified with a ~10-line reproducer independent of Next.js. See filed issue: <nodejs/node_issue_link_goes_here>.

Likely introduced by nodejs/node#61769 (ESM loader cycle reduction), which also caused nodejs/node#62012 (EBADF fstat on zip fds in the same subsystem).

Requested fix

Even though this is upstream-caused, Next.js reaches for a deprecated API (require.extensions, DEP0007 since 2014) at module top level. One-line defensive access would un-break every Yarn PnP user on Node 24.15+ today, without waiting on a Node patch release:

--- a/packages/next/src/build/next-config-ts/require-hook.ts
+++ b/packages/next/src/build/next-config-ts/require-hook.ts
-const oldJSHook = require.extensions['.js'];
+const oldJSHook = require.extensions?.['.js'];
@@
-    for (const ext of extensions){
-      const oldHook = require.extensions[ext] ?? oldJSHook;
-      require.extensions[ext] = function(mod, oldFilename) {
+    for (const ext of extensions){
+      const oldHook = require.extensions?.[ext] ?? oldJSHook;
+      if (!require.extensions) break;
+      require.extensions[ext] = function(mod, oldFilename) {

(Other accesses in the same file would need similar guards, or the whole registerHook function should early-return when require.extensions is falsy.)

No behavior change on working Node versions, since require.extensions has always been defined there.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Mon, 30 Mar 2026 19:15:57 +0000
  Available memory (MB): 31932
  Available CPU cores: 20
Binaries:
  Node: 24.14.1
  npm: 11.11.0
  Yarn: 4.14.1
  pnpm: N/A
Relevant Packages:
  next: 16.2.4
  eslint-config-next: N/A
  react: 19.2.5
  react-dom: 19.2.5
  typescript: 6.0.3
Next.js Config:
  output: export

Which area(s) are affected? (Select all that apply)

Module Resolution

Which stage(s) are affected? (Select all that apply)

next build (local)

Additional context

• Breaks in CI on Bitbucket Pipelines using the node:24-slim image as soon as Bitbucket's cache refreshes to the 24.15.0 layer.
• Workaround for users: pin node:24.14.1-slim (or any Node < 24.15), or switch off Yarn PnP.
• Node issue: require.extensions is undefined on synthetic require for CJS loaded through ESM loader (regression in v24.15.0) nodejs/node#62786

[bmorros94]

Fix submitted in #93248 — adds optional chaining on require.extensions access and early-return guards in registerHook/deregisterHook so the code safely no-ops when require.extensions is undefined (Node 24.15+ under Yarn PnP).

Zero behavioral change on Node versions where require.extensions is defined.