nextjs - 💡(How to fix) Fix Bug: Runtime 500 - clientReferenceManifest undefined for server-only pages in Next.js 15.5.18

Bug: Runtime 500 - clientReferenceManifest undefined for server-only pages in Next.js 15.5.18

Link to the code that reproduces this issue

See reproduction steps below (minimal example included)

To Reproduce

Minimal reproduction:

1. Create Next.js 15.5.18 app with App Router:

npx [email protected] --typescript --app --no-src-dir my-app
cd my-app

1. Create a server-only page without client components:

// app/(marketing)/page.tsx
import type { Metadata } from "next";

export const metadata: Metadata = {
  title: "Home Page",
};

export default function HomePage() {
  return (
    <div>
      <h1>Hello World</h1>
      <p>This is a server-only page with no client components.</p>
    </div>
  );
}

1. Build and start production server:

npm run build
npm start

1. Navigate to http://localhost:3000 → 500 Internal Server Error

2. Check server logs:

Error [InvariantError]: Invariant: Expected clientReferenceManifest to be defined. 
This is a bug in Next.js.
    at k (.next/server/app/(marketing)/page.js:1:4757)
    at m (.next/server/app/(marketing)/page.js:1:7389)
    at n (.next/server/app/(marketing)/page.js:2:1780)
    at responseGenerator (.next/server/app/(marketing)/page.js:2:1918)

Current vs. Expected behavior

Current:

• Build succeeds ✅
• Production runtime crashes with 500 ❌
• Error: "Expected clientReferenceManifest to be defined. This is a bug in Next.js."
• Affects server-only pages without client components

Expected:

• Server-only pages should work at runtime
• clientReferenceManifest should not be required for pages without client components

Provide environment information

Operating System:
  Platform: darwin (macOS)
  Arch: arm64
  Version: Darwin 24.5.0
Binaries:
  Node: 25.9.0
  npm: 10.9.2
Relevant Packages:
  next: 15.5.18
  react: 19.2.3
  react-dom: 19.2.3
  @sentry/nextjs: 10.53.1 (optional, but may trigger the issue)
  typescript: 5.8.3
Next.js Config:
  output: N/A

next.config.js:

const { withSentryConfig } = require("@sentry/nextjs");

const nextConfig = {
  // Standard config
};

module.exports = withSentryConfig(nextConfig, {
  org: "quote-anvil",
  project: "javascript-nextjs",
  silent: !process.env.CI,
  widenClientFileUpload: false, // Disabled due to ENOENT
  tunnelRoute: "/monitoring",
  webpack: {
    automaticVercelMonitors: true,
    treeshake: {
      removeDebugLogging: true,
    },
  },
});

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

• App Router
• Runtime (production)
• Build output

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

• next start (local)
• Vercel (Deployed)

Additional context

Deep dive:

1. Build artifacts:

   • .next/server/app/(marketing)/page.js exists
   • .next/server/app/(marketing)/page.js.nft.json references page_client-reference-manifest.js
   • .next/server/app/(marketing)/page_client-reference-manifest.js does NOT exist

2. Pattern:

   • Pages with client components generate proper manifests and work fine
   • Pages without client components don't generate manifests and crash at runtime
   • Examples working: /pricing, /features (have client components)
   • Examples broken: / (root), /dashboard (server-only until auth check)

3. Build vs Runtime:

   • Build succeeds (no errors)
   • Runtime crashes when accessing affected pages
   • This is a production-only issue (or appears in next start but not next dev)

Attempted workarounds:

1. ❌ Create empty manifest placeholders → Build succeeds, runtime still crashes
2. ❌ Remove export const dynamic = 'force-dynamic' → No effect
3. ❌ Wrap page in 'use client' boundary → Manifest still empty, runtime crashes

Successful workaround:

• Downgrade to Next.js 15.4.x or 14.2.x (not tested yet due to React 19 peer dependency conflicts)

Related issues:

• #82229 (mixed routers, similar error)
• nextjs/saas-starter#174 (build-time, similar error)

Impact:

• Production sites return 500 on affected pages
• Critical severity for landing pages
• No data loss or security impact

Deployment context:

• Vercel production deployments
• Build succeeds, runtime fails
• Multiple consecutive deploys affected (9 in our case)

This appears to be a regression in Next.js 15.5.x where the build process incorrectly assumes all pages need clientReferenceManifest files, even server-only pages. The .nft.json file references these manifests, but they're not generated, causing runtime crashes when Next.js tries to load them.

The error message itself acknowledges this: "This is a bug in Next.js."

Would appreciate guidance on:

1. Is this a known issue with a fix in progress?
2. Should server-only pages require manifests in Next.js 15.5?
3. Is there a configuration to disable manifest generation for specific pages?