Next.js Middleware Not Executing on Protected Routes

1. Incorrect or missing matcher config in middleware.ts for target routes
2. Middleware not in root directory (must be at src/middleware.ts or ./middleware.ts)
3. Middleware exporting default instead of correct middleware function signature
4. Matcher pattern doesn't match actual route paths (regex escaping, prefix issues)
5. Rewrite/redirect not properly returning NextResponse

Create middleware.ts: At project root (not in /app or /pages), export default function:
export function middleware(request: NextRequest) {
// your logic
return NextResponse.next()
}

Configure matcher: Add config to middleware.ts:
export const config = {
matcher: ['/dashboard/:path*', '/admin/:path*']
}

Test execution: Add console.log to middleware, deploy to Vercel (Vercel logs visible in deployment).

Verify paths: Matcher uses regex. Test patterns with regex tester. Use array for multiple patterns.