vercel · ijjk · Nov 14, 2025 · Oct 23, 2025 · Oct 29, 2025 · Oct 30, 2025
diff --git a/packages/next/src/server/next-server.ts b/packages/next/src/server/next-server.ts
@@ -1750,7 +1750,7 @@ export default class NextNodeServer extends BaseServer<
         })
       } finally {
         if (hasRequestBody) {
-          requestData.body.finalize()
+          await requestData.body.finalize()
         }
       }
     } else {

diff --git a/test/e2e/app-dir/actions/app/body-finalize/actions.js b/test/e2e/app-dir/actions/app/body-finalize/actions.js
@@ -0,0 +1,13 @@
+'use server'
+
+/**
+ * @param {number[]} largeJson
+ */
+export async function submitLargePayload(largeJson) {
+  return {
+    success: true,
+    count: largeJson.length,
+    firstId: largeJson[0],
+    lastId: largeJson[largeJson.length - 1],
+  }
+}
diff --git a/test/e2e/app-dir/actions/app/body-finalize/page.js b/test/e2e/app-dir/actions/app/body-finalize/page.js
@@ -0,0 +1,27 @@
+'use client'
+
+import { useMemo, useState } from 'react'
+import { submitLargePayload } from './actions'
+
+export default function Page() {
+  const [result, setResult] = useState(null)
+
+  const largePayload = useMemo(
+    () => new Array(10 * 1024).fill(null).map((_, idx) => idx),
+    []
+  )
+
+  const handleSubmit = async () => {
+    const res = await submitLargePayload(largePayload)
+    setResult(res)
+  }
+
+  return (
+    <div>
+      <button onClick={handleSubmit} id="submit-large">
+        Submit Large Payload
+      </button>
+      {result && <div id="result">{JSON.stringify(result)}</div>}
+    </div>
+  )
+}
diff --git a/test/e2e/app-dir/actions/components/DefaultLayout.tsx b/test/e2e/app-dir/actions/components/DefaultLayout.tsx
@@ -0,0 +1,14 @@
+import React from 'react'
+
+export default function DefaultLayout({
+  children,
+}: {
+  children: React.ReactNode
+}) {
+  return (
+    <html>
+      <head />
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/e2e/app-dir/actions/middleware-node.js b/test/e2e/app-dir/actions/middleware-node.js
@@ -7,6 +7,15 @@ export async function middleware(req) {
     return NextResponse.rewrite(req.nextUrl)
   }
 
+  if (req.method === 'POST' && req.nextUrl.pathname.includes('body-finalize')) {
+    const body = await req.json()
+
+    console.log(
+      'Middleware - Body length: %d bytes',
+      new TextEncoder().encode(JSON.stringify(body)).length
+    )
+  }
+
   return NextResponse.next()
 }
 

diff --git a/test/production/app-dir/actions/app-action-body-finalize-output-standalone.test.ts b/test/production/app-dir/actions/app-action-body-finalize-output-standalone.test.ts
@@ -0,0 +1,87 @@
+import { nextTestSetup } from 'e2e-utils'
+import {
+  findPort,
+  getFullUrl,
+  initNextServerScript,
+  killApp,
+  retry,
+} from 'next-test-utils'
+import webdriver from 'next-webdriver'
+import path from 'node:path'
+import fs from 'fs-extra'
+import os from 'os'
+
+describe('app-dir action body finalize with nodejs middleware and output-standalone', () => {
+  const { next } = nextTestSetup({
+    files: __dirname,
+    skipStart: true,
+  })
+
+  let server: any
+  let appPort: number
+  let tmpFolder: string
+
+  beforeAll(async () => {
+    tmpFolder = path.join(os.tmpdir(), 'next-standalone-' + Date.now())
+    await fs.mkdirp(tmpFolder)
+
+    await next.build()
+    await next.patchFile(
+      '.next/standalone/node_modules/next/dist/server/body-streams.js',
+      (content) => {
+        return content.replace(
+          'async finalize () {',
+          'async finalize () { \nawait new Promise((resolve) => setTimeout(resolve, (Math.random() * 1000) + 1000));\n'
+        )
+      }
+    )
+
+    const distFolder = path.join(tmpFolder, 'test')
+    await fs.move(path.join(next.testDir, '.next/standalone'), distFolder)
+    await fs.move(
+      path.join(next.testDir, '.next/static'),
+      path.join(distFolder, '.next/static')
+    )
+
+    const testServer = path.join(distFolder, 'server.js')
+    appPort = await findPort()
+    server = await initNextServerScript(
+      testServer,
+      /- Local:/,
+      {
+        ...process.env,
+        PORT: appPort.toString(),
+      },
+      undefined,
+      {
+        cwd: distFolder,
+      }
+    )
+  })
+
+  afterAll(async () => {
+    if (server) await killApp(server)
+    if (!process.env.NEXT_TEST_SKIP_CLEANUP) {
+      await fs.remove(tmpFolder).catch(console.error)
+    }
+  })
+
+  it('should handle large payload through server action after nodejs middleware with delayed body finalize', async () => {
+    const browser = await webdriver(getFullUrl(appPort, '/body-finalize'), '')
+
+    try {
+      await browser.elementById('submit-large').click()
+      await retry(async () => {
+        const resultText = await browser.elementById('result').text()
+        const result = JSON.parse(resultText)
+
+        expect(result.success).toBe(true)
+        expect(result.count).toBe(10 * 1024)
+        expect(result.firstId).toBe(0)
+        expect(result.lastId).toBe(10 * 1024 - 1)
+      })
+    } finally {
+      await browser.close()
+    }
+  })
+})
diff --git a/test/production/app-dir/actions/app/body-finalize/actions.js b/test/production/app-dir/actions/app/body-finalize/actions.js
@@ -0,0 +1,13 @@
+'use server'
+
+/**
+ * @param {number[]} largeJson
+ */
+export async function submitLargePayload(largeJson) {
+  return {
+    success: true,
+    count: largeJson.length,
+    firstId: largeJson[0],
+    lastId: largeJson[largeJson.length - 1],
+  }
+}
diff --git a/test/production/app-dir/actions/app/body-finalize/page.js b/test/production/app-dir/actions/app/body-finalize/page.js
@@ -0,0 +1,27 @@
+'use client'
+
+import { useMemo, useState } from 'react'
+import { submitLargePayload } from './actions'
+
+export default function Page() {
+  const [result, setResult] = useState(null)
+
+  const largePayload = useMemo(
+    () => new Array(10 * 1024).fill(null).map((_, idx) => idx),
+    []
+  )
+
+  const handleSubmit = async () => {
+    const res = await submitLargePayload(largePayload)
+    setResult(res)
+  }
+
+  return (
+    <div>
+      <button onClick={handleSubmit} id="submit-large">
+        Submit Large Payload
+      </button>
+      {result && <div id="result">{JSON.stringify(result)}</div>}
+    </div>
+  )
+}
diff --git a/test/production/app-dir/actions/app/layout.js b/test/production/app-dir/actions/app/layout.js
@@ -0,0 +1,8 @@
+export default function RootLayout({ children }) {
+  return (
+    <html>
+      <head />
+      <body>{children}</body>
+    </html>
+  )
+}
diff --git a/test/production/app-dir/actions/middleware.js b/test/production/app-dir/actions/middleware.js
@@ -0,0 +1,27 @@
+// Ensure that https://github.com/vercel/next.js/issues/56286 is fixed.
+import { NextResponse } from 'next/server'
+
+export async function middleware(req) {
+  if (req.nextUrl.pathname.includes('rewrite-to-static-first')) {
+    req.nextUrl.pathname = '/static/first'
+    return NextResponse.rewrite(req.nextUrl)
+  }
+
+  if (req.method === 'POST' && req.nextUrl.pathname.includes('body-finalize')) {
+    const body = await req.json()
+
+    console.log(
+      'Middleware - Body length: %d bytes',
+      new TextEncoder().encode(JSON.stringify(body)).length
+    )
+  }
+
+  return NextResponse.next()
+}
+
+/**
+ * @type {import('next/server').ProxyConfig}
+ */
+export const config = {
+  runtime: 'nodejs',
+}
diff --git a/test/production/app-dir/actions/next.config.js b/test/production/app-dir/actions/next.config.js
@@ -0,0 +1,11 @@
+/** @type {import('next').NextConfig} */
+module.exports = {
+  productionBrowserSourceMaps: true,
+  logging: {
+    fetches: {},
+  },
+  experimental: {
+    serverActions: { bodySizeLimit: '2mb' },
+  },
+  output: 'standalone',
+}
diff --git a/test/production/next-server-nft/next-server-nft.test.ts b/test/production/next-server-nft/next-server-nft.test.ts
@@ -156,7 +156,6 @@ const isReact18 = parseInt(process.env.NEXT_TEST_REACT_VERSION) === 18
          "/node_modules/next/dist/compiled/react-is/cjs/react-is.development.js",
          "/node_modules/next/dist/compiled/react-is/cjs/react-is.production.js",
          "/node_modules/next/dist/compiled/react-is/index.js",
-         "/node_modules/next/dist/compiled/safe-stable-stringify/index.js",
          "/node_modules/next/dist/compiled/send/index.js",
          "/node_modules/next/dist/compiled/source-map/source-map.js",
          "/node_modules/next/dist/compiled/stacktrace-parser/stack-trace-parser.cjs.js",
@@ -270,7 +269,6 @@ const isReact18 = parseInt(process.env.NEXT_TEST_REACT_VERSION) === 18
          "/node_modules/next/dist/compiled/babel-code-frame/index.js",
          "/node_modules/next/dist/compiled/babel/code-frame.js",
          "/node_modules/next/dist/compiled/next-server/server.runtime.prod.js",
-         "/node_modules/next/dist/compiled/safe-stable-stringify/index.js",
          "/node_modules/next/dist/compiled/source-map/source-map.js",
          "/node_modules/next/dist/compiled/stacktrace-parser/stack-trace-parser.cjs.js",
          "/node_modules/next/dist/compiled/ws/index.js",