Ethereum core developers announced that the Fusaka upgrade is planned to go live on the mainnet on Dec. 3. The date was shared during the ACDC #165 developer call. The upgrade will hit Holesky on Oct. 1, Sepolia on Oct. 14, and Hoodi on Oct. 28.
Developers say they will confirm exact dates, times and epoch numbers in the coming days. They also expect blob capacity to double within 2 weeks after activation. The goal is to boost scalability while keeping decentralization and security intact.
Testnet rollout
Developers will stage the upgrade across three testnets before the mainnet launch. Holesky will be the first on Oct. 1. Sepolia follows on Oct. 14. Hoodi is scheduled for Oct. 28.
This sequence gives teams time to test changes under different conditions. Kim, who spoke on the call, said the team will reconfirm the exact launch details soon.
What Fusaka aims to do?
Fusaka is a full hard fork. Its key aim is to help Ethereum scale. The upgrade focuses on changes that let the network handle more data. One visible metric is blob capacity.
Developers expect that capacity to double about 2 weeks after the fork activates. That would mean a 100% increase in blob space available to the network.
Security and decentralization
Core developers stress that Fusaka will try to keep the network secure and decentralized. Any change that boosts capacity must not centralize power.
The team says it will take care to preserve node compatibility and validation rules. That will help make sure a wide set of participants can continue to run nodes and verify the chain.
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Timing and confirmation
While Dec. 3 is the tentative mainnet date, developers want to lock down precise epoch numbers and times. Those details matter for miners, validators and node operators.
Kim said the group will publish final numbers in the next few days, and teams running infrastructure are watching closely to align upgrades and testing windows.
After activation, teams will monitor blob usage and network performance. They will check for any unintended side effects, and the first 2 weeks will be critical because that is when developers expect the biggest change in blob capacity. Any issues found early can be patched or mitigated before they affect a large number of users.
Implications for projects
Projects that build on Ethereum or on layer 2 systems will likely prepare for the upgrade. Developers of rollups, wallets and indexers may update code to handle larger blobs.
Testnet runs give them a chance to validate those changes. Projects that ignore the timeline risk running into compatibility problems when the mainnet fork occurs.
Community response
The timetable demonstrates that the result of the final testing has been made available directly to the community. It indicates that the central teams are proactive in the planned scalability work.
Both users and builders have specific targets to work towards. The aim is to reduce and manage risks while also creating extra time for the teams to respond and adjust.