Next.js sitemap.xml Build Fails with Turbopack Parallel Prerender Race Condition

What this error means

Error: Invariant: failed to find source route /[store]/[lang]/c/sitemap.xml for prerender /[store]/[lang]/c/sitemap.xml — only reproducible on Vercel remote builder with Turbopack parallel workers is a Vercel failure pattern reported for developers trying to fix next.js 16.2.0 regression causing sitemap.xml builds to fail when using force-static dynamic routing on vercel; local next build succeeds but cloud deployment fails. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub vercel/next.js #94041 (open since 2026-05-22, just reported today). Regresssion from 16.1.7 → 16.2.0. Only reproduces on Vercel with 3 parallel Turbopack workers, not locally. Indicates production-deployment-blocking race condition. Category: Deployment (affects production deployments on paid Vercel plans).

Common causes

• GitHub vercel/next.js #94041 (open since 2026-05-22, just reported today). Regresssion from 16.1.7 → 16.2.0. Only reproduces on Vercel with 3 parallel Turbopack workers, not locally. Indicates production-deployment-blocking race condition. Category: Deployment (affects production deployments on paid Vercel plans).

Quick fixes

1. Confirm the exact error signature matches Error: Invariant: failed to find source route /[store]/[lang]/c/sitemap.xml for prerender /[store]/[lang]/c/sitemap.xml — only reproducible on Vercel remote builder with Turbopack parallel workers.
2. Check the Vercel account, local tool state, and provider configuration involved in the failing workflow.
3. Check the build output, project root, and deployment platform configuration before redeploying.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/vercel/next.js/issues/94041

Evidence note: GitHub vercel/next.js #94041 (open since 2026-05-22, just reported today). Regresssion from 16.1.7 → 16.2.0. Only reproduces on Vercel with 3 parallel Turbopack workers, not locally. Indicates production-deployment-blocking race condition. Category: Deployment (affects production deployments on paid Vercel plans).

Related errors

• Deployment

FAQ

What should I check first?

Start with the exact Error: Invariant: failed to find source route /[store]/[lang]/c/sitemap.xml for prerender /[store]/[lang]/c/sitemap.xml — only reproducible on Vercel remote builder with Turbopack parallel workers text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Vercel workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without Error: Invariant: failed to find source route /[store]/[lang]/c/sitemap.xml for prerender /[store]/[lang]/c/sitemap.xml — only reproducible on Vercel remote builder with Turbopack parallel workers.