{"id":661,"date":"2026-05-05T11:51:10","date_gmt":"2026-05-05T11:51:10","guid":{"rendered":"https:\/\/ethereumclassicwallet.com\/articles\/?p=661"},"modified":"2026-05-06T10:46:32","modified_gmt":"2026-05-06T10:46:32","slug":"ethereum-classic-forks-a-chronological-overview-of-etc-network-upgrades","status":"publish","type":"post","link":"https:\/\/ethereumclassicwallet.com\/articles\/ethereum-classic-forks-a-chronological-overview-of-etc-network-upgrades","title":{"rendered":"Ethereum Classic Forks: A Chronological Overview of ETC Network Upgrades"},"content":{"rendered":"
\"\"<\/pre>\n
Ethereum Classic has one of the most unusual histories in crypto. It was not launched as a brand-new blockchain with a clean start and a separate origin story. ETC appeared after the 2016 DAO crisis, when the Ethereum community split over a difficult question: should a blockchain be changed to undo the result of a major smart-contract exploit?<\/p>\n
Most of the Ethereum community supported a hard fork that changed the chain\u2019s state and moved the affected DAO funds. Another part of the community rejected that decision and continued running the original chain without rewriting history. That chain became Ethereum Classic.<\/p>\n
This is why ETC is often described as the continuation of the original Ethereum chain. Its core idea is simple: the blockchain ledger should not be changed just because the outcome is uncomfortable or politically unpopular. At the same time, Ethereum Classic is not against technical upgrades. The network has gone through many hard forks over the years. The difference is that ETC accepts protocol changes that improve security, compatibility, mining, or long-term stability, but rejects forks that manually reverse application-level events.<\/p>\n
The list below follows the main Ethereum Classic hard forks and network upgrades in chronological order.<\/p>\n
Quick Overview of Ethereum Classic Forks<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Date<\/th>\nBlock<\/th>\nFork \/ Upgrade<\/th>\nShort Description<\/th>\n<\/tr>\n<\/thead>\n
July 20, 2016<\/td>\n1,920,000<\/td>\nThe DAO Fork \/ Birth of ETC<\/strong><\/span><\/td>\nThe Ethereum chain split after the DAO crisis. Ethereum accepted a state-changing hard fork, while Ethereum Classic continued the original chain without rewriting history. Source<\/a><\/td>\n<\/tr>\n
October 24, 2016<\/td>\n2,500,000<\/td>\nGas Reprice<\/strong><\/span><\/td>\nAdjusted gas costs for expensive operations to reduce the impact of spam and denial-of-service attacks. Source<\/a><\/td>\n<\/tr>\n
January 13, 2017<\/td>\n3,000,000<\/td>\nDie Hard<\/strong><\/span><\/td>\nDelayed the difficulty bomb, repriced the EXP opcode, and added replay protection by giving ETC its own Chain ID, 61. Source<\/a><\/td>\n<\/tr>\n
December 11, 2017<\/td>\n5,000,000<\/td>\nGotham<\/strong><\/span><\/td>\nIntroduced ETC\u2019s monetary policy under ECIP-1017, including the 5M20 reward reduction model and a capped supply. Source<\/a><\/td>\n<\/tr>\n
May 29, 2018<\/td>\n5,900,000<\/td>\nDefuse Difficulty Bomb<\/strong><\/span><\/td>\nRemoved the difficulty bomb so Ethereum Classic could continue as a long-term proof-of-work chain. Source<\/a><\/td>\n<\/tr>\n
September 12, 2019<\/td>\n8,772,000<\/td>\nAtlantis<\/strong><\/span><\/td>\nAdded Ethereum Spurious Dragon and Byzantium features to improve EVM compatibility. Source<\/a><\/td>\n<\/tr>\n
January 11, 2020<\/td>\n9,573,000<\/td>\nAgharta<\/strong><\/span><\/td>\nAdded Ethereum Constantinople and Petersburg changes, continuing ETC\u2019s compatibility path. Source<\/a><\/td>\n<\/tr>\n
June 1, 2020<\/td>\n10,500,839<\/td>\nPhoenix<\/strong><\/span><\/td>\nImplemented Ethereum Istanbul features on ETC to keep smart-contract behavior closer to Ethereum\u2019s EVM standards. Source<\/a><\/td>\n<\/tr>\n
November 28, 2020<\/td>\n11,700,000<\/td>\nThanos<\/strong><\/span><\/td>\nChanged the mining algorithm from Ethash to ETChash and reduced the DAG size, making ETC mining possible again on 3 GB and 4 GB GPUs. Source<\/a><\/td>\n<\/tr>\n
July 23, 2021<\/td>\n13,189,133<\/td>\nMagneto<\/strong><\/span><\/td>\nBrought Ethereum Berlin features to ETC, including changes to gas costs, transaction types, and access lists. Source<\/a><\/td>\n<\/tr>\n
February 12, 2022<\/td>\n14,525,000<\/td>\nMystique<\/strong><\/span><\/td>\nAdded selected Ethereum London changes, but did not include EIP-1559 or BASEFEE because they did not fit ETC\u2019s monetary model. Source<\/a><\/td>\n<\/tr>\n
February 5, 2024<\/td>\n19,250,000<\/td>\nSpiral<\/strong><\/span><\/td>\nAdded Shanghai-era EVM changes and kept ETC aligned with newer Ethereum smart-contract standards. Source<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
The DAO Fork and the Birth of Ethereum Classic<\/h3>\n
Date: July 20, 2016
Block: 1,920,000<\/p>\n
Strictly speaking, this was not an Ethereum Classic upgrade. It was the event that created Ethereum Classic as a separate chain.<\/p>\n
After The DAO exploit, the Ethereum community faced a hard choice. One option was to change the blockchain\u2019s state and move the affected funds. The other was to leave the chain as it was, even though the result was controversial and painful for many users.<\/p>\n
The Ethereum Foundation-backed chain chose the first path and performed a hard fork. The chain that refused to rewrite history continued separately and became Ethereum Classic. Source<\/a><\/p>\n
This moment defined ETC\u2019s identity. Ethereum Classic became the chain that prioritized immutability and the principle that smart contracts should run as written. That does not mean ETC never changes its protocol. It means that ETC draws a line between technical network upgrades and direct intervention into application-level outcomes.<\/p>\n
Gas Reprice<\/h3>\n
Date: October 24, 2016
Block: 2,500,000<\/p>\n
Gas Reprice was the first major independent protocol upgrade of Ethereum Classic after the DAO split. Its purpose was very practical: protect the network from spam and denial-of-service attacks.<\/p>\n
At that time, some Ethereum Virtual Machine operations were too cheap compared with the real amount of work they forced nodes to do. Attackers could exploit this imbalance by flooding the network with operations that were inexpensive for them but costly for nodes to process.<\/p>\n
Gas Reprice adjusted gas costs for those operations. In simple terms, it made certain types of spam attacks more expensive and helped keep the chain stable. Source<\/a><\/p>\n
This fork also showed an important point about Ethereum Classic. ETC is not against hard forks as a technical tool. It is against hard forks that rewrite history. When the goal is to improve security, stability, or protocol behavior, ETC can and does upgrade.<\/p>\n
Die Hard<\/h3>\n
Date: January 13, 2017
Block: 3,000,000<\/p>\n
Die Hard was one of the most important early Ethereum Classic upgrades. It delayed the difficulty bomb, repriced the EXP opcode, and introduced replay protection by giving Ethereum Classic its own Chain ID: 61. Source<\/a><\/p>\n
Replay protection mattered because Ethereum and Ethereum Classic had recently split from the same chain history. Without replay protection, a transaction signed for one chain could potentially be copied and replayed on the other. Giving ETC its own Chain ID helped separate the two networks at the transaction level.<\/p>\n
The difficulty bomb was another major issue. It had been designed into Ethereum\u2019s early roadmap to make proof-of-work mining harder over time and push the network toward future changes. For ETC, which chose to remain proof-of-work, that mechanism became a problem. Die Hard delayed the bomb and gave the community more time to make a long-term decision.<\/p>\n
Gotham<\/h3>\n
Date: December 11, 2017
Block: 5,000,000<\/p>\n
Gotham introduced Ethereum Classic\u2019s monetary policy under ECIP-1017. This was a major economic fork, not just a technical maintenance update.<\/p>\n
The upgrade introduced the 5M20 model, where block rewards are reduced by 20% every 5 million blocks. It also placed an upper limit on ETC\u2019s total supply, around 210.7 million ETC. Source<\/a><\/p>\n
This made ETC\u2019s monetary structure more predictable and more similar in spirit to Bitcoin than to Ethereum. Instead of an open-ended issuance model, ETC moved toward a fixed-supply proof-of-work asset.<\/p>\n
For miners, investors, exchanges, and long-term holders, Gotham made the rules easier to understand. It gave ETC a clearer economic identity: proof-of-work, capped supply, and a predictable reduction schedule.<\/p>\n
Defuse Difficulty Bomb<\/h3>\n
Date: May 29, 2018
Block: 5,900,000<\/p>\n
The Defuse Difficulty Bomb upgrade permanently removed the difficulty bomb problem from Ethereum Classic. Earlier, Die Hard had only delayed it. Defuse Difficulty Bomb made the long-term decision.<\/p>\n
This fork confirmed that ETC would not follow Ethereum\u2019s path toward proof-of-stake. Instead, Ethereum Classic would continue as a proof-of-work blockchain. Source<\/a><\/p>\n
Technically, this protected the network from an artificial rise in mining difficulty. Philosophically, it made ETC\u2019s position clearer. Proof-of-work was not just a temporary phase for Ethereum Classic. It became part of the chain\u2019s long-term identity.<\/p>\n
Atlantis<\/h3>\n
Date: September 12, 2019
Block: 8,772,000<\/p>\n
Atlantis brought Ethereum Classic closer to Ethereum\u2019s EVM standard by adding changes from Ethereum\u2019s Spurious Dragon and Byzantium upgrades. Source<\/a><\/p>\n
This was part of a larger ETC strategy: preserve its own identity, but stay compatible with the wider Ethereum developer ecosystem where possible.<\/p>\n
That compatibility matters. ETC uses Ethereum-style smart contracts, so developers, wallets, block explorers, exchanges, and infrastructure providers benefit when ETC behaves similarly to Ethereum at the EVM level.<\/p>\n
Atlantis did not change ETC\u2019s basic philosophy. It did not change proof-of-work or the monetary policy. Instead, it helped keep Ethereum Classic technically useful for smart-contract development.<\/p>\n
Agharta<\/h3>\n
Date: January 11, 2020
Block: 9,573,000<\/p>\n
Agharta continued the same compatibility path. It added Ethereum\u2019s Constantinople and Petersburg protocol changes to Ethereum Classic. Source<\/a><\/p>\n
For ordinary users, this fork was not very visible. It did not create a new coin, change mining, or alter ETC\u2019s supply rules. But for developers and infrastructure providers, it mattered.<\/p>\n
Better EVM compatibility means fewer problems when working with smart contracts, wallets, libraries, and blockchain tools. Agharta helped ETC stay closer to the Ethereum technical stack while keeping its own consensus and economic model.<\/p>\n
Phoenix<\/h3>\n
Date: June 1, 2020
Block: 10,500,839<\/p>\n
Phoenix implemented Ethereum\u2019s Istanbul upgrade features on Ethereum Classic. Source<\/a><\/p>\n
By this point, Ethereum Classic\u2019s approach had become fairly clear. ETC would not copy Ethereum blindly, but it would adopt useful EVM upgrades when they made sense for the network.<\/p>\n
Phoenix improved compatibility with modern Ethereum-style smart contracts and tooling. This was important because ETC did not want to become technically isolated. A blockchain can have strong principles, but if developers cannot easily build on it or support it, the ecosystem becomes weaker.<\/p>\n
Phoenix helped ETC remain part of the broader EVM world while keeping its own proof-of-work identity.<\/p>\n
Thanos<\/h3>\n
Date: November 28, 2020
Block: 11,700,000<\/p>\n
Thanos was different from Atlantis, Agharta, and Phoenix. It was not mainly about EVM compatibility. It was about mining.<\/p>\n
The upgrade implemented ECIP-1099 and changed Ethereum Classic\u2019s mining algorithm from Ethash to ETChash. The key practical effect was reducing the DAG size, which made it possible for 3 GB and 4 GB GPUs to mine ETC again. Source<\/a><\/p>\n
This mattered because mining accessibility affects decentralization. If only a narrow group of miners with specific hardware can participate, the mining base becomes more concentrated. Thanos tried to make ETC mining accessible to more GPU miners again.<\/p>\n
The timing was also important. Ethereum Classic had faced serious security concerns, including 51% attack incidents. Thanos was part of a broader effort to strengthen the network\u2019s proof-of-work security by improving mining participation.<\/p>\n
Magneto<\/h3>\n
Date: July 23, 2021
Block: 13,189,133<\/p>\n
Magneto was another compatibility-focused upgrade for Ethereum Classic. It brought several Ethereum Berlin changes to ETC through ECIP-1103, including EIP-2565, EIP-2929, EIP-2718, and EIP-2930. These updates affected gas pricing, transaction formats, and access lists. Source<\/a><\/p>\n
For most regular users, Magneto was not the kind of fork that changed how ETC looked or felt from the outside. It did not create a new coin, change the supply model, or replace the mining algorithm. Its value was more practical: it helped ETC stay compatible with the wider Ethereum Virtual Machine ecosystem.<\/p>\n
That matters because ETC still uses Ethereum-style smart contracts. Developers, wallets, exchanges, block explorers, and infrastructure providers all benefit when ETC behaves in a way that is close to Ethereum\u2019s EVM standards. The closer the technical base is, the easier it is to support ETC without building everything from scratch.<\/p>\n
In simple terms, Magneto was a maintenance and modernization fork. It kept Ethereum Classic technically relevant while allowing the network to preserve its own identity: proof-of-work consensus, fixed monetary policy, and no DAO-style rewriting of chain history.<\/p>\n
Mystique<\/h3>\n
Date: February 12, 2022
Block: 14,525,000<\/p>\n
Mystique brought selected Ethereum London changes to Ethereum Classic through ECIP-1104. But this was not a full copy of Ethereum\u2019s London upgrade. Source<\/a><\/p>\n
The most important point is that ETC did not include EIP-1559 or BASEFEE. Ethereum\u2019s London upgrade introduced a new fee market where part of the transaction fee is burned. Ethereum Classic did not adopt that model because it did not fit ETC\u2019s monetary policy and economic design.<\/p>\n
This makes Mystique a good example of how Ethereum Classic handles compatibility. ETC is willing to adopt useful EVM improvements, but it does not automatically import every Ethereum change. If a change conflicts with ETC\u2019s monetary model or long-term direction, the network can leave it out.<\/p>\n
Spiral<\/h3>\n
Date: February 5, 2024
Block: 19,250,000<\/p>\n
Spiral activated at block 19,250,000 on February 5, 2024. It brought Ethereum Classic closer to Shanghai-era EVM standards and continued the long-running effort to keep ETC compatible with modern Ethereum-style smart-contract tooling. Source<\/a><\/p>\n
Like Atlantis, Agharta, Phoenix, Magneto, and Mystique, Spiral was mainly a compatibility upgrade. It helped ETC stay aligned with newer EVM behavior without changing the chain\u2019s basic identity.<\/p>\n
Spiral also came after years of work to keep Ethereum Classic useful for developers while preserving its core principles. ETC remained proof-of-work. It kept its own monetary policy. It did not move toward Ethereum\u2019s proof-of-stake model. But it still continued to modernize its technical base.<\/p>\n
Conclusion<\/h2>\n
Ethereum Classic\u2019s fork history shows that ETC is not a frozen or abandoned version of Ethereum. The network has changed many times. But those changes have followed a fairly consistent logic.<\/p>\n
The early forks were about survival and separation. Gas Reprice helped protect the network from spam. Die Hard added replay protection and delayed the difficulty bomb. Gotham created ETC\u2019s monetary policy. Defuse Difficulty Bomb confirmed the chain\u2019s long-term proof-of-work direction.<\/p>\n
The later forks were mostly about compatibility. Atlantis, Agharta, Phoenix, Magneto, Mystique, and Spiral helped ETC stay close to Ethereum\u2019s EVM standards. That made life easier for developers, wallets, exchanges, block explorers, and infrastructure providers.<\/p>\n
Thanos stands apart because it focused on mining. By moving from Ethash to ETChash and reducing the DAG size, it tried to make ETC mining more accessible and strengthen the proof-of-work base of the network.<\/p>\n
Taken together, these forks explain what Ethereum Classic is trying to be: a proof-of-work smart-contract blockchain with predictable monetary rules, strong immutability principles, and enough EVM compatibility to remain useful in the broader crypto ecosystem.<\/p>\n","protected":false},"excerpt":{"rendered":"
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