Mismatching worker version with pdfjs-dist as a direct dependency (answered ✅)

[lirbank]

If you've installed pdfjs-dist as a direct dependency and the version is not matching the pdfjs-dist that react-pdf depends on, you may get an error that looks like this:

Warning: UnknownErrorException: The API version "3.6.172" does not match the Worker version "3.7.107".

In this case I have this "pdfjs-dist": "3.7.107" in my package.json, but react-pdf depends on "pdfjs-dist": "3.6.172". To solve this, make sure to use the worker provided by the pdfjs-dist version that react-pdf specifically depends on, eg:

pdfjs.GlobalWorkerOptions.workerSrc = new URL(
  // "pdfjs-dist/build/pdf.worker.min.js",
  "react-pdf/node_modules/pdfjs-dist/build/pdf.worker.min.js",
  import.meta.url
).toString();

Unfortunately you have to change this back to "pdfjs-dist/build/pdf.worker.min.js" if the direct dependency version matches react-pdf's version, since NPM will move pdfjs-dist to the top level node_modules if the versions match (eg if I were to change my package.json to "pdfjs-dist": "3.6.172" in the example above).

I am using Next.js 13 and NPM 9.

[wojtekmaj]

Thanks for the tip!

My recommendation would be to also keep these versions in sync and avoid duplication - pdfjs-dist is suuuuuper heavy package, so it matters more than usual.

[lirbank]

Good point! Do you think react-pdf's dependency on pdfjs-dist be relaxed a bit? Right now it's an exact dependency so one could not upgrade pdfjs-dist to the latest version before react-pdf is upgraded.

[lirbank]

Eg. changing this

https://github.com/wojtekmaj/react-pdf/blob/main/package.json#LL42C8-L42C8

from

  "pdfjs-dist": "3.6.172",

to

  "pdfjs-dist": ">=3.6.172",

or something like that.

[wojtekmaj]

I would love to, but historically this lead to significant issues. PDF.js is released with complete disregard for semver. This means that ANY PDF.js version update that has not been tested can potentially render React-PDF useless. Or throwing gazillions of warnings at best.

I think that's the only exception to using ^ range I've made across all my 50+ packages.