isolatedDevBuild

The experimental isolatedDevBuild option separates development and production build outputs into different directories. When enabled, the development server (next dev) writes its output to .next/dev instead of .next, preventing conflicts when running next dev and next build concurrently.

This is especially helpful when automated tools (for example, AI agents) run next build to validate changes while your development server is running, ensuring the dev server is not affected by changes made by the build process.

This feature is enabled by default to keep development and production outputs separate and prevent conflicts.

Configuration

To opt out of this feature, set isolatedDevBuild to false in your configuration:

import type { NextConfig } from 'next'
 
const nextConfig: NextConfig = {
  experimental: {
    isolatedDevBuild: false, // defaults to true
  },
}
 
export default nextConfig

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