I don't know enough to be able to understand the error message out (one of
my main complaints for Guix is the atrocious error messages these things
throw), but what happens if you try to run with no substitutes?:

```
guix pull --no-substitutes
```

If that fails, maybe try something like the following (convoluted way to
try to run your commands with a newer guix binary (also assuming your local
binary might be broken)):
```
guix build --no-substitutes guix
guix build --check guix
guix shell guix
guix pull
guix shell guix
guix package -u
```

Also, are you able to post your `channels.scm` file? It is probably located
at `$HOME/.config/guix/channels.scm`

v/r,

Aaron