I couldn't figure out what it was, but it was definitely a problem with NixOS itself, possibly with expired root certificates or something like that. The upgrad

I couldn't figure out what it was, but it was definitely a problem with NixOS itself, possibly with expired root certificates or something like that. The upgrade command couldn't connect to the nixos servers. I know there was at least one root certificate that expired in the past 3 years, so maybe I just caught a bad interval for not upgrading.