I had to reinstall Nix and home-manager recently on my Mac, because for some reason home-manager switch stopped working. After a bit of searching and trying out a bunch of fixes I found what worked. The working solution started with a full reinstall of Nix, and that starts with emptying the generated Nix volume with disk utility. The workflow was roughly as follows:Empty nix volume with disk utilityInstall multi-user Nixbash