Rolling Back
# /run/current-system/bin/switch-to-configuration boot
# nixos-rebuild switch --rollback
Nix Store Corruption
# nixos-rebuild switch --repair
# nix-store --verify --check-contents --repair
Alternative Binary Caches
Disable: nixos-rebiuld switch --option use-binary-caches false
Change: nixos-rebiuld switch --option binary-caches http://my-cache.example.org/