The Ethereum Foundation has officially announced the mainnet deployment of the London upgrade, one of the most anticipated network updates in Ethereum’s history. Posted by core developer Tim Beiko on July 15, 2021, the announcement confirmed that London will go live at block 12,965,000, expected to be mined between August 3 and August 5, 2021.
TL;DR
- Ethereum London upgrade confirmed for block 12,965,000, expected August 3-5, 2021
- Five EIPs included, headlined by the controversial EIP-1559 fee market overhaul
- All major client releases have been issued with London-compatible versions
- Bug bounties doubled for any London-related vulnerabilities ahead of activation
- OpenEthereum client will be deprecated following the London upgrade
What the London Upgrade Includes
The London upgrade bundles five Ethereum Improvement Proposals (EIPs) into a single hard fork. The centerpiece is EIP-1559, a fundamental change to Ethereum’s transaction fee mechanism that introduces a base fee burned on every transaction, rather than being paid to miners. This has been one of the most debated changes in Ethereum’s history, with some mining pools publicly opposing it due to the reduction in miner revenue.
Alongside EIP-1559, the upgrade includes EIP-3198, which adds a BASEFEE opcode allowing smart contracts to read the current base fee — a critical enabler for DeFi protocols that need to factor gas costs into their logic. EIP-3529 reduces gas refund incentives, closing a loophole that was being exploited for arbitrage. EIP-3541 rejects new contracts starting with the 0xEF byte, reserving that prefix for future opcodes. Finally, EIP-3554 delays the difficulty bomb to December 1, 2021, buying time before Ethereum transitions to proof-of-stake.
Client Releases and Node Operator Requirements
The Ethereum Foundation released updated client versions for all major implementations. Go-ethereum (geth) version 1.10.6, Nethermind 1.10.79, Erigon 2021.07.04-alpha, Besu 21.7.2, and OpenEthereum v3.3.0-rc.4 all support the London upgrade on mainnet. Node operators running any of these clients must upgrade before the fork block.
Miners, in particular, need to take an extra step: because London doubles the effective block gas limit, miners must manually set their gas limit target to twice their current value. For instance, a miner targeting 15,000,000 gas per block would need to adjust to 30,000,000. Failure to do so would result in producing undersized blocks.
OpenEthereum Deprecation and Security Push
The announcement also marked the beginning of the end for OpenEthereum (formerly Parity), which will be deprecated after the London upgrade. The OpenEthereum team is coordinating with Erigon on a transition path for users. Meanwhile, the Ethereum Foundation has doubled all bug bounties for London-related vulnerabilities, specifically encouraging researchers to look for cross-client consensus issues between geth, Besu, Nethermind, OpenEthereum, and Erigon.
Market Context
At the time of the announcement, Ethereum was trading at approximately $1,911, down roughly 4.2% over 24 hours and nearly 10% over the previous week. Bitcoin sat at around $31,780. The broader crypto market had been in a cooling period following the dramatic highs of May 2021, and the London upgrade represented a key narrative catalyst that many analysts believed could help stabilize sentiment around Ethereum’s long-term value proposition — particularly through the fee-burning mechanism of EIP-1559.
Why This Matters
The London upgrade is one of the most consequential changes to Ethereum’s economic model. By burning transaction fees through EIP-1559, Ethereum introduces a deflationary pressure that could fundamentally alter ETH’s supply dynamics. For DeFi protocols, NFT marketplaces, and everyday users, the new fee mechanism promises more predictable gas costs. For miners, it represents a significant revenue reduction. And for the broader Ethereum community, it marks one of the final major upgrades before the network transitions fully to proof-of-stake. The stakes are high, and the countdown to block 12,965,000 is well underway.
Disclaimer: This article is for informational purposes only and does not constitute financial advice. Always do your own research before making any investment decisions.
been waiting for 1559 since the miner debates started. the threats to fork off were peak comedy. how did that work out for them lol
the OpenEthereum deprecation announcement buried in there is actually huge. anyone still running OE nodes needs to migrate before August or they fall off consensus
Doubling bug bounties for London-related vulnerabilities is smart. This is the biggest fee market change Ethereum has ever attempted and a single bug could cost millions in MEV.