migrating-middleware-to-proxy

Migrating middleware.ts to proxy.ts in Next.js 16 requires renaming the file, changing the middleware export to proxy, keeping NextResponse and matcher config identical, and moving authentication logic to server components or route handlers instead.

Next.js 16 renames middleware.ts to proxy.ts and the middleware export to proxy to align the API with its new proxy-based pattern and address security implications of the previous middleware architecture.

Proxy.ts handles headers, logging, and URL rewriting. Authentication logic must move to server components or route handlers; keeping auth out of proxy.ts enforces the separation between request routing and identity verification.

No, matcher configuration remains identical during migration from middleware.ts to proxy.ts; only the file name, export name, and auth delegation change.

No, authentication logic must be excluded from proxy.ts and delegated to server components or route handlers. Proxy.ts is designed for request interception tasks like headers and rewriting, not identity verification.

Next.js 16 middleware migration addresses the CVE-2025-29927 breaking change by enforcing separation of concerns: proxy.ts handles routing concerns while server components and route handlers handle authentication, eliminating security vulnerabilities from mixed responsibilities.