As per what seemed to be the popular demand, the protocol rules have been updated incompatibly with the existing Ethereum protocol. Users have essentially moved to a new blockchain and left the old one behind. At time of publication, well over 90 percent of hash power on the Ethereum network had moved to the new chain. This fork effectively reverts the existence of the DAO and will reclaim almost all funds taken by an attacker a month ago, to return them to the original investors.

But the hard fork also marks the launch of a spin-off project: Ethereum Classic. Ethereum Classic continues on the existing Ethereum blockchain and has not implemented the hard fork code to "undo" the DAO. According to the project's website, this is because "Ethereum Classic intends to keep the original censorship-resistant Ethereum going" and "provide an alternative for people who strongly disagree with DAO bailout."