Opening an issue here as requested in the support email (I initially asked on Twitter what was the best PoC, and was redirected to the support) 🙂

Yarn 2 doesn't support the --cache-folder command-line option (it always was problematic, because users had to specify it at every single command). This causes a crash on Netlify when using Yarn together with the v2 (currently flagged experimental, fortunately).

Additionally, starting from Yarn 2 we no longer have different logic between the Yarn cache and the offline mirrors. The directory pointed by the cache-folder key will be populated with archives, and as such it becomes possible (and recommended in various situations) to add the cache to the repository (amongst other things, it enables Zero-installs). However, this doesn't work if Netlify configures a different cache location than the default one.

We're currently hitting this issue with the Yarn 2 Netlify instance (example), but it's likely your customers would encounter it as well once we start publishing formal releases. I'd be happy to help find out a solution (I lead Yarn's development) 🙂