vercel-upgrade-migrationClaude Skill

Vercel Upgrade Migration

Overview

Safely upgrade Vercel CLI, Node.js runtime versions, and framework versions (especially Next.js) on Vercel. Covers breaking change detection, vercel.json schema changes, and rollback strategy.

Current State

!vercel --version 2>/dev/null || echo 'Vercel CLI not installed' !node --version 2>/dev/null || echo 'N/A' !cat package.json 2>/dev/null | jq -r '.dependencies.next // "no next.js"' 2>/dev/null || echo 'N/A'

Prerequisites

• Current Vercel CLI installed
• Git for version control
• Test suite available
• Preview deployment for testing

Instructions

Step 1: Check Current Versions

# Current CLI version
vercel --version

# Current Node.js runtime on Vercel
cat package.json | jq '.engines.node'
# Or check vercel.json
cat vercel.json | jq '.functions'

# Check for available CLI updates
npm outdated -g vercel

# Check framework version
npm ls next react

Step 2: Upgrade Vercel CLI

# Upgrade to latest
npm install -g vercel@latest

# Or specific version
npm install -g vercel@39

# Verify
vercel --version

CLI breaking changes to watch for:

• v28+: vercel env pull output format changed
• v32+: vercel dev uses new function runtime
• v37+: vercel.json builds property deprecated in favor of framework detection

Step 3: Upgrade Node.js Runtime

// package.json — specify the Node.js version
{
  "engines": {
    "node": "20.x"
  }
}

Available runtimes on Vercel:

Runtime	Status	EOL
Node.js 18.x	Supported	April 2025
Node.js 20.x	Active LTS (recommended)	April 2026
Node.js 22.x	Current	October 2027

# Test locally with the target Node version first
nvm use 20
npm test
npm run build

Step 4: Upgrade Next.js on Vercel

# Use the Next.js upgrade codemod
npx @next/codemod@latest upgrade

# Or manual upgrade
npm install next@latest react@latest react-dom@latest

# Check for breaking changes
npx @next/codemod --dry-run

Key Next.js migration points:

• 13 → 14: App Router stable, Turbopack available, Server Actions stable
• 14 → 15: fetch no longer cached by default, cookies() is async, NextRequest.geo removed (use geolocation() from @vercel/functions)
• vercel.json changes: rewrites/redirects in next.config.js take precedence over vercel.json

Step 5: Test in Preview Before Production

# Create a branch for the upgrade
git checkout -b upgrade/vercel-cli-39

# Make changes and push
git add -A && git commit -m "chore: upgrade vercel CLI and Node.js 20"
git push -u origin upgrade/vercel-cli-39

# Vercel auto-deploys a preview — test it
vercel ls | head -3
curl -s https://my-app-git-upgrade-vercel-cli-39-team.vercel.app/api/health

# Run full test suite against preview
npm test -- --env=preview

Step 6: Rollback Strategy

# If the upgrade breaks production — instant rollback
vercel rollback

# Pin to a specific CLI version in CI
# .github/workflows/deploy.yml
# - run: npm install -g vercel@38  # pin to known good version

# Revert Node.js runtime
# Change engines.node back in package.json
# Push and redeploy

vercel.json Schema Migration

Deprecated builds property (v2 → current):

// Old (deprecated):
{
  "builds": [
    { "src": "api/**/*.ts", "use": "@vercel/node" }
  ]
}

// New (framework auto-detection):
{
  "functions": {
    "api/**/*.ts": {
      "runtime": "nodejs20.x",
      "maxDuration": 30
    }
  }
}

Output

• Vercel CLI upgraded to latest version
• Node.js runtime version updated in package.json
• Framework upgraded with codemods applied
• Preview deployment tested before production promotion
• Rollback strategy documented

Error Handling

Error	Cause	Solution
Build failed after Node upgrade	Dependency incompatible with new Node	Check npm ls for native modules, rebuild
Module not found after Next.js upgrade	Import paths changed	Run npx @next/codemod for automatic fixes
vercel.json validation error	Schema changed in new CLI version	Remove deprecated builds, use functions
FUNCTION_INVOCATION_FAILED	Runtime API removed in new Node.js	Check Node.js changelog for removed APIs
Preview works but prod fails	Env vars differ between environments	Verify production env vars match preview

Resources

• Vercel CLI Changelog
• Node.js Runtime on Vercel
• Next.js Upgrade Guide
• vercel.json Reference

Next Steps

For CI/CD integration, see vercel-ci-integration.