Konrad Hinsen <konrad.hinsen@fastmail.net> writes:

> Hi Ludo and Chris,
>
>> Could it be that those old systems were talking to hydra.gnu.org and
>> thus not getting any substitutes?
>>
>>   https://lists.gnu.org/archive/html/info-guix/2019-06/msg00001.html
>
> That's what happened to me on my oldest Guix installation (hosted on
> Ubuntu). I had done regular pulls on my user account, but not on the
> root account, meaning that I was running an ancient daemon that tried to
> connect to hydra.

Yes, it's possible this was the cause.  Thank you to everyone who
replied!  In the end, I was able to run "guix pull".

-- 
Chris