Internet Computer upgrades its subnets one at a time instead of all at once Upgrading @dfinity's Internet Computer takes two kinds of votes: onchain governance first elects a new software version into the approved list, then separate proposals move each subnet onto it. Subnets, the groups of node machines that each run a slice of the network, upgrade on their own schedules. Different subnets can run different versions at the same time. When a subnet's turn comes, its nodes agree on a block height where the handover happens. The old version computes everything through that block, and the new version takes over at the next one. State crosses between the two via a catch-up package, a signed snapshot that the new software resumes from, per Internet Computer documentation.