As the cryptocurrency market suffered a brutal selloff on February 24, 2019, the Ethereum community was quietly preparing for one of the most significant network upgrades in the blockchain’s history. The Constantinople hard fork, later combined with the St. Petersburg upgrade, was scheduled to activate at block 7,280,000 — projected for February 28, 2019. The timing could not have been more dramatic, with Ethereum’s price plunging more than 10% on the same day the upgrade was being finalized.
TL;DR
- Ethereum Constantinople/St. Petersburg upgrade confirmed for block 7,280,000 (~February 28, 2019)
- ETH price dropped 10.6% to approximately $141 amid broad market selloff
- The upgrade was previously delayed from January 2019 due to a security vulnerability
- Constantinople reduces block rewards from 3 ETH to 2 ETH and introduces EIPs for efficiency
- DeFi applications on Ethereum stood to benefit from reduced gas costs and improved contract functionality
Constantinople: A Long Time Coming
The Constantinople upgrade had been a long and bumpy road for the Ethereum development community. Originally scheduled to go live in January 2019, the upgrade was abruptly postponed after a critical security vulnerability was discovered just days before the planned activation. The vulnerability, related to EIP-1283, could have potentially allowed replay attacks on certain smart contracts, posing a risk to the entire ecosystem.
The Ethereum community acted swiftly. On February 22, 2019, the official Ethereum blog published the Constantinople/St. Petersburg upgrade announcement, confirming that the dual upgrade would activate at block 7,280,000. The inclusion of the St. Petersburg fork alongside Constantinople was a direct response to the January security scare — St. Petersburg would disable the problematic EIP-1283 while Constantinople implemented the remaining improvements.
What the Upgrade Actually Changed
For DeFi users and developers building on Ethereum, the Constantinople upgrade brought several important changes. The most widely discussed was the reduction of the block reward from 3 ETH to 2 ETH, a move designed to manage Ethereum’s inflation rate as the network matured. For miners, this represented a significant 33% reduction in mining revenue per block.
Beyond the block reward reduction, Constantinople introduced several Ethereum Improvement Proposals (EIPs) aimed at making the network more efficient. These included optimizations to the Ethereum Virtual Machine (EVM) that would reduce gas costs for certain operations, making smart contract interactions cheaper for users. For the growing DeFi ecosystem — which in early 2019 was still in its nascent stages but expanding rapidly — lower gas costs meant more accessible financial products.
The Market Context: ETH in Freefall
The timing of the Constantinople announcement was particularly striking. On February 24, just two days after the official upgrade announcement, Ethereum suffered a dramatic 10.6% decline, falling to approximately $141. The selloff was part of a broader market crash that saw Bitcoin drop below $3,900 and the total cryptocurrency market capitalization shed $15 billion.
Trading data from Kraken showed that ETH volume reached $80.1 million on February 24, reflecting intense selling pressure. Ethereum’s market capitalization fell to approximately $14.3 billion, a fraction of the $130+ billion it had commanded at the peak of the bull market just over a year earlier. The irony was not lost on market observers: Ethereum was preparing for a technically significant upgrade while its price was in freefall.
DeFi in Early 2019: Building the Foundations
While the term “DeFi” had not yet entered mainstream crypto vocabulary in February 2019, the building blocks were already in place. Protocols like MakerDAO, which had launched its Dai stablecoin in late 2017, were gaining traction. Compound Finance had recently launched its lending protocol, and Uniswap would debut just a few months later in November 2019.
The Constantinople upgrade’s gas cost reductions were particularly relevant for these early DeFi protocols. Every transaction on Ethereum required gas, and for financial applications that needed to execute complex smart contract interactions, gas costs could be prohibitive. By optimizing certain EVM operations, Constantinople helped lay the groundwork for the DeFi explosion that would follow in 2020 and beyond.
Why This Matters
The Constantinople/St. Petersburg upgrade represents a pivotal moment in Ethereum’s evolution. It demonstrated the network’s ability to execute complex, coordinated upgrades even in the face of security challenges and market turmoil. For the DeFi ecosystem, the gas optimizations introduced in Constantinople were an important step toward making decentralized financial products economically viable for everyday users. The upgrade also marked an important milestone in Ethereum’s journey toward proof-of-stake, as the block reward reduction was part of a broader strategy to manage the network’s economic security during the transition. In retrospect, February 2019 was the quiet before the storm — the DeFi summer of 2020 was still over a year away, but the foundations were being laid during the depths of crypto winter.
Disclaimer: This article is for informational purposes only and does not constitute financial advice. Past performance is not indicative of future results. Always conduct your own research before making investment decisions.
the delay from january to february because of the reentrancy bug found by trail of bits was actually good process. better safe than another DAO situation
eip_1459_fan Trail of Bits finding the reentrancy bug during a delayed audit is insane luck. a few days earlier or later and it might have shipped to mainnet
trail_of_bits_fan literally one auditor caught the bug that could have repeat of the DAO situation. no idea why people dont talk about this more
eth_archaeologist_ Trail of Bits catching that reentrancy bug during a delayed audit is the luckiest break in ethereum history. shipping it in january wouldve been worse than the DAO
block_7280k_ Trail of Bits catching that reentrancy bug during the delayed audit saved ethereum from another DAO situation. insane how close it was
ETH down 10.6% to $141 on the same day Constantinople was being finalized for launch. talk about terrible timing for a network upgrade
Wei C. ETH at $141 during the fork and now its 4 figures. devs who shipped under that pressure built the foundation
reducing gas costs and block rewards during a 10% crash. the DeFi users who stuck around through this are the ones who made life-changing money in 2020-21
gas_tracker_ constantinople was the first time ethereum proved it could do monetary policy changes without chain splitting. thats the real legacy
the security vulnerability that delayed Constantinople from January to February probably saved the network. rushing a hard fork with a known reentrancy bug would have been catastrophic for DeFi
DeFi TVL was basically nothing in Feb 2019 so Constantinople reducing gas costs didnt matter much short term. but it laid the groundwork for the 2020 explosion
DeFi TVL was under 200M in feb 2019. constantinople was building the plumbing for what became a trillion dollar ecosystem
Nikos G. defi TVL was basically zero back then. constantinople reducing block rewards 3 to 2 eth was the real supply shock nobody talks about
block_reward_cut reducing from 3 to 2 ETH was the real precedent for the merge supply shock. people forget constantinople set the stage for EIP-1559 and the ultrasonic money narrative
lisa_hodl_ the january delay was the best thing that happened to ethereum in 2019. shipping a reentrancy bug to mainnet would have been catastrophic
the reentrancy bug was caught by a third party auditor too. community found it, not the core devs. imagine if it had shipped in january as planned
eth at 141 during a 10.6% crash and the dev team still shipped the upgrade on schedule. that delivery under pressure built real credibility
3 ETH to 2 ETH block rewards and ETH was at 141 dollars. miners were genuinely panicking about the revenue cut. turned out to be the best thing that happened since it reduced sell pressure
EIP-1283 almost killed ethereum. the reentrancy pattern it introduced was identical to the DAO bug. Trail of Bits earned their fee that week
Constantinople delayed from January because of a reentrancy vulnerability found in EIP-1283. the fix was literally St Petersburg shipping alongside. two upgrades in one fork to patch a bug in the other
gasstation_v shipping two upgrades in one fork to patch each other is peak ethereum energy. Constantinople and St Petersburg were literally a bug and its fix deployed simultaneously
ETH at $141 feels fake now. we were all panic selling and the devs just quietly shipped a hard fork. different era
Dimitri O. $141 feels fake now but back then we were all sweating. the devs shipping Constantinople on schedule during a 10% crash built massive credibility
block reward going from 3 to 2 ETH was the dry run for the merge supply narrative. everyone obsessed over gas costs but the issuance cut was the real game
Stefan H. the 3 to 2 ETH reduction was the blueprint for EIP-1559 and the merge. constantinople proved the community could ship monetary policy changes without fracturing