Turbopack build fails 'Failed to collect page data' on CMS-fed sitemap.xml in Next.js 16

What this error means

Turbopack build fails Failed to collect page data for /sitemap.xml — works with --webpack flag is a Vercel failure pattern reported for developers trying to fix next.js turbopack build crash when app/sitemap.ts fetches data from external cms (sanity, etc.). Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Vercel next.js #93144 (2026-04-23): Next.js 16.2.3 Turbopack fails to collect page data for CMS-fetched routes. Works around with —webpack. Affects Vercel-deployed apps using dynamic route generation. Category: Deployment (Vercel/Turbopack). Distinct from generic ‘Vercel build command failed’ covered error.

Common causes

• Vercel next.js #93144 (2026-04-23): Next.js 16.2.3 Turbopack fails to collect page data for CMS-fetched routes. Works around with —webpack. Affects Vercel-deployed apps using dynamic route generation. Category: Deployment (Vercel/Turbopack). Distinct from generic ‘Vercel build command failed’ covered error.

Quick fixes

1. Confirm the exact error signature matches Turbopack build fails Failed to collect page data for /sitemap.xml — works with --webpack flag.
2. Check the Vercel account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

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/93144

Evidence note: Vercel next.js #93144 (2026-04-23): Next.js 16.2.3 Turbopack fails to collect page data for CMS-fetched routes. Works around with —webpack. Affects Vercel-deployed apps using dynamic route generation. Category: Deployment (Vercel/Turbopack). Distinct from generic ‘Vercel build command failed’ covered error.

Related errors

• Deployment

FAQ

What should I check first?

Start with the exact Turbopack build fails Failed to collect page data for /sitemap.xml — works with --webpack flag 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 Turbopack build fails Failed to collect page data for /sitemap.xml — works with --webpack flag.