App Router build fails with “Expected workUnitAsyncStorage to have a store” when prerendering /dashboard and /_not-found (Next 16.0.8 + Turbopack)

[Nalcakars]

Hi everyone,
I’m consistently getting a prerendering crash during production build with Next.js 16.0.8 (Turbopack) — the build stops with:

Error occurred prerendering page "/dashboard". Read more: https://nextjs.org/docs/messages/prerender-error Error occurred prerendering page "/_not-found". Read more: https://nextjs.org/docs/messages/prerender-error Error [InvariantError]: Invariant: Expected workUnitAsyncStorage to have a store. This is a bug in Next.js. at K (C:\apps\happsbi-dashboard\.next\server\chunks\ssr\[root-of-the-server]__092ddb26._.js:1:83546) at br (C:\apps\happsbi-dashboard\.next\server\chunks\ssr\[root-of-the-server]__092ddb26._.js:4:7769) Export encountered an error on /dashboard/page: /dashboard, exiting the build. Export encountered an error on /_not-found/page: /_not-found, exiting the build.

It clearly says “This is a bug in Next.js”, and looks related to async context inside prerender / PPR / dynamic IO.

npm run dev works perfectly — no runtime errors.

npm run build fails consistently during prerendering.

Errors alternate between /_global-error, /_not-found, and /dashboard/reports/....

I already tried all known workarounds:

Added export const dynamic = 'force-dynamic' and fetchCache = 'force-no-store' to root layout.

Added custom app/not-found.tsx and app/global-error.tsx (with 'use client').

Split dashboard page into a server + client component (page.tsx + DashboardClient.tsx).

Verified that no headers(), cookies(), useRouter(), usePathname(), etc. are called from server components.

Despite this, the build still fails with the same InvariantError.

I'm waiting for your support, thank you

Additional information

Environment

Next.js: 16.0.8 (Turbopack)

Node.js: 20.x (Windows)

Framework: App Router

Frontend stack: Mantine + TypeScript + React 19

Build command: npm run build

OS: Windows Server 2019 (PowerShell terminal)

Example

No response

[icyJoseph]

Please try to build with npx next build --debug-prerender that one outputs a lot more info

[Nalcakars]

thanks again for the pointers,

I tried the command you suggested,

`⚠ Prerendering is running in debug mode. Note: This may affect performance and should not be used for production.
▲ Next.js 16.0.8 (Turbopack)

• Environments: .env.local, .env.production

Creating an optimized production build ...
✓ Compiled successfully in 4.2s
✓ Finished TypeScript in 5.3s
✓ Collecting page data using 23 workers in 652.7ms

Error occurred prerendering page "/global-error". Read more: https://nextjs.org/docs/messages/prerender-error
C:\apps\happsbi-dashboard\node_modules\next\dist\server\app-render\work-unit-async-storage.external.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\apps\happsbi-dashboard.next\server\chunks\ssr[root-of-the-server]__092ddb26..js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\compiled\next-server\app-page-turbo.runtime.prod.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\server\lib\trace\tracer.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\export\routes\app-page.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\trace\trace.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\export\worker.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
Error [InvariantError]: Invariant: Expected workUnitAsyncStorage to have a store. This is a bug in Next.js.
at createServerSearchParamsForServerPage (C:\apps\happsbi-dashboard.next\server\chunks\ssr[root-of-the-server]__092ddb26..js:6334:82)
at createMetadataComponents (C:\apps\happsbi-dashboard.next\server\chunks\ssr[root-of-the-server]__092ddb26..js:9609:26)

Export encountered errors on following paths:
/_global-error/page: /_global-error
`

So even when I focus only on app/page.tsx with --debug-build-paths, the build still dies while prerendering /_global-error, with the same workUnitAsyncStorage invariant.

This is not a monorepo – it’s a single Next app, no separate packages feeding components into app/.

[icyJoseph]

MMm wild, this also used --debug-prerender too right?

There's an issue when building, that in exchange for speed, it drops some info, that's why --debug-prerender was created. Whether or not that should be the case, and --debug-prerender benefits should be in build directly, is another discussion topic.

But long story, short, a failure in a page, ends up reflecting in one of those fallback files instead. Anyway.

I think the sourceMap error is likely caused by the attempt at showing a better error stack via --debug-prerender.

I wonder if the issue is in the root layout, somehow... Are you using a custom server? At this point I'd start to remove components from root layout.tsx and page.tsx, until I get a good build. The single path command build should speed things up.

[Nalcakars]

I temporarily replaced my app/layout.tsx with a fully minimal layout (no Mantine, no providers, no global styles, just html/body):

export const dynamic = 'force-dynamic';
export const fetchCache = 'force-no-store';

export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang="tr">
      <body>{children}</body>
    </html>
  );
} 

Then I ran:

npx next build --debug-build-paths="app/page.tsx" --debug-prerender

result:

⚠ Prerendering is running in debug mode. Note: This may affect performance and should not be used for production.
▲ Next.js 16.0.8 (Turbopack)
- Environments: .env.local, .env.production

Creating an optimized production build ...
✓ Compiled successfully in 3.5s
✓ Finished TypeScript in 4.9s
✓ Collecting page data using 23 workers in 679.8ms

Error occurred prerendering page "/_global-error". Read more: https://nextjs.org/docs/messages/prerender-error
C:\apps\happsbi-dashboard\node_modules\next\dist\server\app-render\work-unit-async-storage.external.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\apps\happsbi-dashboard\.next\server\chunks\ssr\[root-of-the-server]__092ddb26._.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\compiled\next-server\app-page-turbo.runtime.prod.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\server\lib\trace\tracer.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\export\routes\app-page.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\trace\trace.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
C:\Apps\happsbi-dashboard\node_modules\next\dist\export\worker.js: Invalid source map. Only conformant source maps can be used to find the original code. Cause: Error: sourceMapURL could not be parsed
Error [InvariantError]: Invariant: Expected workUnitAsyncStorage to have a store. This is a bug in Next.js.
    at createServerSearchParamsForServerPage (C:\apps\happsbi-dashboard\.next\server\chunks\ssr\[root-of-the-server]__092ddb26._.js:6334:82)
    at createMetadataComponents (C:\apps\happsbi-dashboard\.next\server\chunks\ssr\[root-of-the-server]__092ddb26._.js:9609:26)

> Export encountered errors on following paths:
        /_global-error/page: /_global-error

the fact that the issue persists with a minimal root layout makes me think this might be an internal bug in how _global-error prerendering + workUnitAsyncStorage is wired.

[icyJoseph]

May I see a print of your app file tree?

[icyJoseph]

Why are you using, does removing them bring about more issues, or perhaps unwanted implicit behavior?

export const dynamic = 'force-dynamic';
export const fetchCache = 'force-no-store';