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

[Bill Trost]

Eelco Dolstra wrote:
    Bill Trost wrote:
    > 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?
    
    ...
    
    To revert to the old Nix store schema, do:
    
    $ echo -n 5 > /nix/var/nix/db/schema

That helped, but the next run of nix-env totally destroyed the profile. I
probably should have run "nix-env --rollback" immediately after
downgrading the schema. Instead, I had to dig a slightly older version of
nix-env out of the store and run "nix-env -u \*" manually to recover
everything.

In any case, it appears to be all better now.

Thanks,
Bill