pageExtensions
By default, Next.js accepts files with the following extensions: .tsx, .ts, .jsx, .js. This can be modified to allow other extensions like markdown (.md, .mdx).next.config.js const withMDX = require('@next/mdx')()
 
/** @type {import('next').NextConfig} */
const nextConfig = {
  pageExtensions: ['ts', 'tsx', 'mdx'],
  experimental: {
    mdxRs: true,
  },
}