seems like this is the fix

"build": "rm -rf .next/cache/* && next build",

What builder are you using?

It looks like Railpack does in fact cache .next/cache.

And, as it happens, Nixpacks does too.

So, to answer your question about docs, the answer would be that it'll be in the documentation of whichever build system you're using.

I’m using the default one (Railpack). What I couldn’t find in the docs:

• How to turn off this caching

• What the exact cache keys are (I presume it’s fingerprinting the lockfile?)

Both of these are pretty critical to being able to resolve the issue. The “manually remove” approach I went with is a hack.

Also, usually deploying services have a “delete caches” and “redeploy without cache” button. So that’s a feature request I guess. I’m not sure how one is supposed to solve these types of issues otherwise.

The cache key should actually just be next. As far as turning it off, I'm not sure that's implemented at the moment, short of what you're doing right now.