Ethereum has evolved through a series of crucial upgrades since its inception. Each hard fork and improvement proposal has shaped the network into what it is today. For anyone involved in the Ethereum ecosystem, understanding these milestones is essential.
Blockchain upgrades differ from traditional software updates. Instead of a centralized entity pushing a new version, decentralized networks require consensus through hard forks. Miners and validators must update their clients to follow the new rules. The upgraded chain becomes the mainnet, while the old one is typically abandoned. However, sometimes communities disagree, leading to permanent splits—as seen with Ethereum and Ethereum Classic.
Frontier (July 30, 2015)
Frontier was Ethereum's first live release, aimed at developers. It was a bare-bones, command-line-based system, often considered a beta version. The name reflects the risky, opportunity-filled environment of the early Ethereum network, much like the American frontier era.
This release initially set a gas limit of 5,000 per block. Shortly after, the Frontier Thawing upgrade removed this limit and set the default gas price to 50 gwei. It also introduced the difficulty bomb—a mechanism designed to gradually increase mining difficulty and encourage the transition to Proof-of-Stake (PoS). When activated, this bomb would usher in the "Ice Age," making Proof-of-Work (PoW) mining impractical. Thus, from the very beginning, Ethereum was committed to moving to PoS.
At the time of this upgrade, ETH was priced at $1.24.
Homestead (March 14, 2016)
The Homestead upgrade was Ethereum's second major version, symbolizing the transition from a frontier settlement to a more established home. This release introduced the first Ethereum Improvement Proposals (EIPs), specifically EIP-2, EIP-7, and EIP-8.
EIP-2 increased the gas cost for contract creation from 21,000 to 53,000. EIP-7 added a new opcode, DELEGATECALL, enabling better code reuse. EIP-8 improved the devp2p networking protocol for forward compatibility.
ETH was trading at $12.50 during this upgrade.
The DAO Fork (July 20, 2016)
This was not a planned upgrade but a necessary response to a crisis. The DAO, a decentralized autonomous organization built on Ethereum, raised $150 million in ETH—about 14% of all circulating ether at the time. A vulnerability in its smart contract led to a massive hack.
After failed attempts to mitigate the damage, the community decided to execute a hard fork to recover the stolen funds. This decision deeply divided the community. Those who believed in "code is law" continued to maintain the original chain, now known as Ethereum Classic (ETC).
At the time of the fork, ETH was valued at $12.54.
Byzantium (October 16, 2017)
Byzantium was part of the larger Metropolis upgrade, which aimed to transform Ethereum into a mature platform. This phase was split into multiple upgrades due to its complexity.
A key focus was advancing the transition to PoS. EIP-649 delayed the difficulty bomb by 1.5 years and reduced the block reward from 5 ETH to 3 ETH. This reduction was a step toward making PoW less profitable and easing the eventual shift to PoS.
EIP-214 was another critical change, introducing restrictions on state modifications during contract calls to enhance security after The DAO incident.
ETH was priced at $334.32 during this upgrade.
Constantinople and St. Petersburg (February 28, 2019)
Originally planned as one upgrade, Constantinople was delayed due to a security vulnerability discovered by ChainSecurity. It was eventually implemented alongside the St. Petersburg upgrade in the same block.
EIP-1234 reduced the block reward from 3 ETH to 2 ETH, further discouraging PoW mining. The difficulty bomb was again delayed by 12 months.
EIP-1014 introduced the CREATE2 opcode, which allowed developers to compute contract addresses before deployment. This enabled state channel solutions, similar to Bitcoin’s Lightning Network, where transactions could be computed off-chain and settled on-chain.
ETH was valued at $136.29 at this time.
Muir Glacier (January 2, 2020)
Just a month after the Istanbul upgrade, Ethereum underwent another emergency hard fork. The difficulty bomb was set to activate earlier than expected, and with PoS not yet ready, Muir Glacier was implemented to delay it.
The name Muir Glacier—referring to a vanished glacier in Alaska—symbolized the temporary "melting" of the difficulty bomb.
ETH was trading at $127.18.
Beacon Chain Launch (December 1, 2020)
This marked a major step toward PoS. The Beacon Chain, which runs in parallel to the main PoW chain, was launched. It allowed users to stake ETH and participate in consensus, setting the stage for the eventual merge.
ETH was priced at $586.23.
Berlin (April 15, 2021)
Berlin began the tradition of naming upgrades after Devcon host cities. This upgrade included several optimizations, such as EIP-2929, which increased gas costs for certain opcodes to mitigate denial-of-service risks.
ETH was valued at $2,454 during this upgrade.
London (August 5, 2021)
The London upgrade introduced EIP-1559, one of the most significant changes to Ethereum's economic model. Instead of a pure auction system for transaction fees, EIP-1559 split fees into a base fee (which is burned) and a priority fee (paid to miners). This mechanism started making ETH a deflationary asset.
To date, over 3.2 million ETH, worth billions of dollars, has been burned.
ETH was trading at $2,621 at the time.
Paris Upgrade - The Merge (September 15, 2022)
The Merge was one of Ethereum's most anticipated milestones. It combined the execution layer (mainnet) with the consensus layer (Beacon Chain), transitioning Ethereum fully to PoS. EIP-3675 officially implemented the PoS consensus mechanism.
However, one issue remained: staked ETH could not be withdrawn. This locked early stakers’ funds during a market downturn, highlighting the need for a withdrawal mechanism to avoid centralization risks.
ETH was priced at $1,472.
Shanghai Upgrade (April 12, 2023)
The Shanghai upgrade enabled staking withdrawals, allowing users to unstake their ETH. This encouraged more participation in staking, with over 19 million ETH now staked. It also paved the way for the growth of LSDfi (Liquid Staking Derivatives finance).
ETH was valued at $1,917.
Upcoming Cancun Upgrade
The Cancun upgrade, expected in late 2023, focuses on scalability. A key feature is EIP-4844, which introduces proto-danksharding. This adds a new transaction type called Blob, allowing Layer 2 solutions to store data more cheaply and significantly reduce transaction costs.
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Frequently Asked Questions
What is a hard fork?
A hard fork is a backward-incompatible upgrade to a blockchain. It requires all nodes to update their software to continue participating in the network. If some nodes refuse, a chain split can occur.
Why does Ethereum use a difficulty bomb?
The difficulty bomb gradually increases mining difficulty, making PoW less profitable over time. This encourages miners to support the transition to Proof-of-Stake.
What is EIP-1559?
EIP-1559 changed Ethereum's fee market by introducing a base fee that is burned. This reduces ETH supply over time and makes transaction fees more predictable.
How does the Beacon Chain work?
The Beacon Chain is Ethereum's PoS consensus layer. It manages validators, processes attestations, and coordinates consensus without executing transactions.
What are the benefits of the Cancun upgrade?
Cancun will lower Layer 2 transaction fees by introducing blob transactions. This improves scalability and user experience for applications built on Ethereum.
Can staked ETH be unstaked after Shanghai?
Yes, the Shanghai upgrade enabled withdrawals for staked ETH, making staking more flexible and attractive to users.
Ethereum's journey is a testament to long-term vision and meticulous execution. From its first version to the upcoming Cancun upgrade, each step has been guided by a clear roadmap—all conceived when Vitalik Buterin was just 21.