Ethereum core developers have confirmed a tentative roadmap for the network’s next major upgrade, Fusaka, during Thursday’s All Core Developers Consensus (ACDC) call.
The upgrade, designed to further scale the blockchain, is now scheduled for early December, with follow-up changes aimed at more than doubling blob capacity in the weeks after.
Before the Fusaka upgrade reaches Ethereum’s mainnet, developers will push the code through three public test networks in October.
If those tests proceed smoothly, the mainnet activation is targeted for Dec. 3. Developers noted that exact epoch numbers and timing will be confirmed in the coming days.
Blob Capacity Expansion via BPO Forks
While Fusaka itself won’t immediately change blob parameters, the call outlined a phased approach to scaling blob availability through so-called Blob Parameter Only (BPO) forks.
One week after Fusaka BPO-1 will raise the blog target/max from 6/9 to 10/15, then one week later BPO-2 will push the limit to 14/21.
These incremental changes are based on performance observed on the Fusaka Devnet-5 and are intended to safely expand capacity without requiring client-side software updates.
Blobs, introduced in March’s Dencun upgrade, allow Ethereum to store large amounts of rollup transaction data more efficiently, reducing costs for users of layer-2 scaling networks.
Looking Ahead
Ethereum researcher Christine Kim, who reported the call highlights on X, noted that additional BPOs remain on the roadmap for Fusaka, although only the first two were scheduled in this week’s call.
A detailed timeline of the Fusaka and BPO activations is available via Ethereum’s public notes.
The Fusaka rollout follows May’s Pectra upgrade, which introduced validator staking changes and new account abstraction features, underscoring Ethereum’s ongoing push to optimize scalability and network efficiency.
Source: https://www.coindesk.com/business/2025/09/19/ethereum-developers-set-fusaka-upgrade-for-december-ahead-of-blob-capacity-boosts
