Thanks. Still got errors, albeit a different set of errors, after changing the cache to the one in the link.
By the way, I am a NixOS newbie in China, and can that be the cause of the problem? Improvements to cache.nixos.org (help test the new config!) says:
I would also appreciate any feedback from users who hit the cache from Asia/Australia for example. Previously, these users would normally connect somewhere like Singapore/Hong Kong, which would then later connect all the way to
us-east-1. This would require a very large TCP handshake across the globe, making latency quite bad, especially in the case of many small misses (e.g. for many narinfo files which do not exist, which would effectively be a worst-case.)
Long story short, in ~/.config/nix/nix.conf I put “stalled-download-timeout = 99999999” (just an arbitrarily large number). I guess you can put this into /etc/nix/nix.conf if you prefer. PROBLEM FIXED!!!
What is the equivalent way to set timeout in /etc/configuration.nix?