Another simple way to reproduce the issue without having to clone a repo:

1. Create a new NextJS project with npx create-next-app@latest my-project and accept all the default values
2. cd my-project
3. yarn install
4. yarn build --> See that the build is successful
5. yarn add tesseract.js
6. Create file src/app/api/route.ts and add the following code to it:

import { createWorker } from "tesseract.js";

export async function GET(req: Request) {
  const worker = await createWorker("eng");
  return new Response();
}

7. yarn build --> See the error

When I ran your repo I got a file path (Cannot find module) error. This indicates that the worker code is not being found automatically, so the path needs to be set manually. This can be done using the workerPath argument. In your case, I think this would look like the following:

const worker = await createWorker("eng", 1, {workerPath: "./node_modules/tesseract.js/src/worker-script/node/index.js"});

For context, Tesseract.js "workers" get their own web worker (browser) or worker thread (Node.js), which is independent code that uses a different entry point. When Tesseract.js is used on its own, this entrypoint should be identified automatically. However, this may not hold with build systems implemented by various frameworks, as these build systems copy around files in a way that violates Tesseract.js's assumptions for where files are located.

That is actually very helpful information. It works now. Thanks a lot :-)

I encountered this issue and setting workerPath didn't help. I fixed the issue by adding tesseract.js to serverComponentsExternalPackages in my next config.

In my case, I modified next.config.mjs and vercel.json:

const nextConfig = {
  experimental: {
    serverComponentsExternalPackages: ['tesseract.js'],
    outputFileTracingIncludes: {
      '/api/**/*': ['./node_modules/**/*.wasm', './node_modules/**/*.proto']
    }
  }
};

{
  "functions": {
    "app/api/**/route.ts": {
      "includeFiles": "node_modules/tesseract.js-core/tesseract-core-simd.wasm",
      "memory": 1024,
      "maxDuration": 60
    }
  }
}

Sources: https://github.com/orgs/vercel/discussions/1278