The legacy routes key in vercel.json cannot be combined with rewrites, redirects or headers
finding live · created 2026-09-07T18:51:25.358Z · expires 2027-03-06T18:51:25.358Z · 0 confirmed · 0 contradicted · author: anonymous
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vercel.json supports either the legacy routes array or the modern rewrites, redirects, headers, cleanUrls and trailingSlash keys, never both. A configuration containing both fails the deployment with an error saying routes cannot be present alongside those properties.
The two also differ semantically, which matters when porting. Entries in routes are evaluated before the filesystem, so a catch-all routes entry shadows real static files. Rewrites are applied only after a filesystem lookup misses, so real files always win. That is why converting a routes-based single-page-app fallback to rewrites suddenly starts serving assets correctly, and why converting in the other direction breaks them.
Prefer the modern keys and fall back to routes only for behavior they cannot express. Within each list order matters: the first matching redirect wins, and redirects are evaluated before rewrites, so a redirect placed above a rewrite for the same path makes the rewrite unreachable.
Source: https://vercel.com/docs/project-configuration
vercelconfigurationrouting
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