Nextjs upgrade

Next.js Upgrade Protocol

Automated and manual migration steps for Next.js version upgrades (e.g., v14 → v15).

Priority: P1 (OPERATIONAL)

Implementation Guidelines

• Upgrade Detection: Always check package.json for versions of next, react, and react-dom.
• Planning: For major version jumps (v13 to v15), perform an incremental upgrade (v13 -> v14, then v14 -> v15). Follow the official Next.js Migration Guides.
• Automated Codemods: Use npx @next/codemod@latest <transform> <path> to automate syntax migration.
• Breaking Changes (v15): Respond to the next-async-request-api transform by ensuring params, searchParams, cookies(), and headers() are awaited.
• React Parity: Upgrade react and react-dom to match Next.js peer dependencies (e.g., React 19 for Next.js 15).
• Validation: Run next dev and next build after each incremental step. Check Console errors for hydration warnings.
• Reporting: Report all codemod failures or manual fixes needed to the team.

3. Dependency Update

Upgrade Next.js and peer dependencies in sync:

# Using npm
npm install next@latest react@latest react-dom@latest

# Update Types
npm install --save-dev @types/react@latest @types/react-dom@latest

4. Manual Verification Rules

1. Async Context: Verify all uses of cookies(), headers(), and route params are now awaited.
2. Metadata: Ensure generateMetadata types match the new async params signature.
3. Caching: In v15+, fetch defaults to { cache: 'no-store' }. If you need the old behavior, explicitly set { cache: 'force-cache' }.

5. Testing Build

• Run npm run build immediately after codemods and package updates.
• Check for "Hydration failed" or "Turbopack" compatibility errors if using --turbo.

Anti-Patterns

• No major version skipping: Upgrade one major version at a time (13→14, then 14→15).
• No manual breaking-change fixes: Always run npx @next/codemod@latest transforms first.
• No assumed caching behavior post-upgrade: v15 defaults to no-store; audit all fetch calls.
• No async page functions in Pages Router: export default async function Page() is fatal.