How to Fix Next.js Metadata API Error in AI-Built Apps
Next.js metadata generation fails or produces incorrect SEO tags. AI-generated metadata code often mixes the old Head component approach with the new Metadata API, or returns invalid formats.
Error messages you might see
Error: You are attempting to export "metadata" from a component marked with "use client"Type 'string' is not assignable to type 'Metadata'Why this happens in AI-generated code
Metadata in client components
AI adds `export const metadata` to files with 'use client' directive, which Next.js doesn't support.
Mixing Head and Metadata API
AI uses both `next/head` and the Metadata API in the same project, causing conflicts.
Invalid metadata format
AI returns strings or incorrect structures instead of the proper Metadata object shape.
How to fix it
Export metadata from server components only
Move `export const metadata` or `export function generateMetadata()` to server components (files without 'use client').
Use generateMetadata for dynamic values
For pages with dynamic metadata, export an async `generateMetadata` function that receives params and returns a Metadata object.
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Frequently asked questions
Can I use next/head with the App Router?
No. The App Router uses the Metadata API exclusively. Use `export const metadata` or `generateMetadata()` instead of `<Head>`.
How do I set metadata for all pages?
Export metadata from your root `layout.tsx`. Child pages can override specific fields by exporting their own metadata.
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