Ethereum classic has removed its so-called "difficulty bomb."
Designed to increase the difficulty of mining over time, the code was a feature of the original ethereum blockchain (which later split into ethereum classic and ethereum) in 2016. The successful network change took place at block 5,900,000, according to available network data and statements from developers involved in the project.
The upgrade puts both technical and ideological distance between the ethereum classic and ethereum blockchains.
While the ethereum community remains committed to transitioning to a proof-of-stake system, the ethereum classic community has elected to continue using a proof-of-work system because its members contend that, of the various ways to achieve consensus over block validation, it resists centralization best.
More specifically, advocates argue that proof-of-work systems require their validators (miners) to continuously invest in hardware and therefore in the blockchain.
In contrast, they argue that proof-of-stake systems give unfair advantages to institutional stakeholders and easily create 'economic majorities' because the influence of stakeholders is determined by the amount of capital they invest in the system.
Therefore, the decision to remove the bomb via a hard fork was both a technical necessity - such that mining remains feasible - and an ethical statement.
Deliberation on the fork started as early as 2016, and due to the extensive discussions, the upgrade was not expected to be controversial or complicated.
While it is difficult to account for exact percentages, developers involved with the project told CoinDesk that most exchange nodes and mining pools had updated their software well before the fork.
There was no indication of any ill effects or bugs in the hours immediately after the fork. The upgrade is expected to reduce the amount of time it takes to create a block.