I have a fumadocs site that was working until a few days ago. Now it returns 404 on every page when next start but it works just fine on next dev.

I have the following next.config.mjs:

import { createMDX } from "fumadocs-mdx/next";

const withMDX = createMDX();

/** @type {import('next').NextConfig} */
const config = {
  serverExternalPackages: ["@takumi-rs/core", "typescript", "twoslash"],
  // output: "export",
  reactStrictMode: true,
  basePath: "/docs",
  // trailingSlash: true,
  images: {
    unoptimized: true,
  },
  async rewrites() {
    return {
      afterFiles: [
        {
          source: "/:path*.md",
          destination: "/llms.mdx/docs/:path*",
        },
      ],
    };
  },
};

export default withMDX(config);

And this souce.config.ts:

import { defineConfig, defineDocs } from "fumadocs-mdx/config";
import { metaSchema, pageSchema } from "fumadocs-core/source/schema";
import { remarkSteps } from "fumadocs-core/mdx-plugins/remark-steps";
import { remarkMdxMermaid } from 'fumadocs-core/mdx-plugins';
import { rehypeCodeDefaultOptions } from "fumadocs-core/mdx-plugins";

// You can customize Zod schemas for frontmatter and `meta.json` here
// see https://fumadocs.dev/docs/mdx/collections
export const docs = defineDocs({
  dir: "content",
  docs: {
    schema: pageSchema,
    postprocess: {
      includeProcessedMarkdown: true,
    },
  },
  meta: {
    schema: metaSchema,
  },
});

export default defineConfig({
  mdxOptions: {
    remarkPlugins: [remarkSteps, remarkMdxMermaid],
    rehypeCodeOptions: {
      themes: {
        light: "github-light",
        dark: "github-dark",
      },
      transformers: [
        ...(rehypeCodeDefaultOptions.transformers ?? []),
      ],

      // important: Shiki doesn't support lazy loading languages for codeblocks in Twoslash popups
      // make sure to define them first (e.g. the common ones)
      langs: ["js", "jsx", "ts", "tsx"],
    },
  },
});