Your project contains a directory named app/. Since Next.js 13, this is a reserved name.

To use the new app directory and its features, please add appDir: true to your configuration in next.config.js under experimental.

/** @type {import('next').NextConfig} */
const nextConfig = {
  experimental: {
    appDir: true,
  },
}

module.exports = nextConfig

If you do not want to use the new app/ directory features yet, but have a directory named app/, rename the directory to something else.

• Next.js 13 App directory
• App directory documentation