[Nix-dev] nix suddenly unusable as of version upgrade

[Bill Trost]

Hi, all,

Yesterday I did an update from the nixpkgs-unstable channel and at some
point during the upgrade process is automatically upgraded to schema
version six. I thought that was fine, but now when I try to run nix-env or
nix-channel, I get the error message

  error: current Nix store schema is version 6, but I only support 5

Uh, now what? How do I recover from this situation?

Thanks,
Bill