How to fix "Cannot install with 'frozen-lockfile' because pnpm-lock.yaml is absent" in pnpm

I've been setting up a new project CI/CD pipeline with pnpm and GitHub Actions and encountered a weird issue. It was throwing an error:

Cannot install with "frozen-lockfile" because pnpm-lock.yaml is absent

This didn't make much sense to me because the pnpm-lock.yaml file was present in the repository. I tried running a clean pnpm install, but it didn't help. Then I discovered that a few lines above in the logs, there was a warning:

WARN Ignoring not compatible lockfile at pnpm-lock.yaml

This pushed me in the right direction. I found out that my CI was running an old version of pnpm, or simply a much different version than the one on my local machine.

To fix the issue, I first replaced pnpm/action-setup@v2 with the newer version pnpm/action-setup@v4 and set the version of pnpm to the one I have locally.

- uses: pnpm/action-setup@v4
  with:
    version: 9.5.0