Error when trying to uninstall while running watchman.

[ilyagr]

I had the following error while running the nix/nix-installer uninstall. (I was trying to reinstall Nix to update the build user UIDs). I'm not 100% this is actionable, but I thought I'd share.

I debugged with lsof /nix, and the reason was that I had watchman installed with Nix and it was running. One way to reproduce this would be to also install jj (I think nix profile install nixpkgs#jujutsu should do it), configure it to use Watchman, and jj git clone https://github.com/martinvonz/jj; cd jj; jj status. Then, watchman would be running in the same way it was for me and uninstalling Nix would fail in the same way.

Solution/Workaround

The solution for me was to killall watchman, wait a bit, check that lsof /nix no longer showed anything, and then run the uninstaller again.

Speculation

Perhaps the uninstaller should also run lsof /nix before trying to destroy the drive, and either give a friendly error message or try to kill those processes for me.

Error

Error: 
   0: Error reverting
   0: Action `create_apfs_volume` errored
      Failed to execute command with status 1 `"/usr/sbin/diskutil" "apfs" "deleteVolume" "Nix Store"`, stdout: Started APFS operation
      Deleting APFS Volume from its APFS Container
      Unmounting disk3s7
      The volume "Nix Store" on disk3s7 couldn't be unmounted because it is in use by process 0 (kernel)

      stderr: Error: -69888: Couldn't unmount disk

Metadata

key	value
version	0.15.1
os	macos
arch	aarch64

[cole-h]

Thanks for the report!

Yeah, at this point at least, I don't know how we can fix this.

Maybe we should just try to delete the volume, and if it can't be deleted, print a big ole warning / error at the end, but otherwise continue to uninstall.

Upon reinstall, we'd notice that it already exists and will either use it (under some circumstances I don't quite remember enough about to list here), or will ask you to try to delete it again -- we could add a note that "you may need to reboot before running this".