Ethereum core developers have confirmed the activation date for the Fusaka network upgrade on December 3, 2025, marking the second hard fork of the year. The announcement followed consensus in the All Core Developers Consensus Layer call #168, where participants agreed on the final testnet performance and readiness criteria. Slot 13,164,544 on the mainnet has been designated as the activation block, expected to be reached at approximately 21:49 UTC. The coordinated decision reflects continued investment in protocol improvement.
The primary feature of the Fusaka upgrade is Peer Data Availability Sampling (PeerDAS), which allows validators to verify portions of block data instead of complete blob downloads. This improvement reduces bandwidth consumption and computational overhead, benefiting both full nodes and layer-2 networks. Early estimates suggest bandwidth requirements may drop by over 60%, enabling more cost-effective validation services. PeerDAS integration aims to enhance network scalability and support increasing transaction volumes amid growing decentralized finance activity.
Fusaka follows the successful deployment on Hoodi, the final public testnet, which processed over 50,000 blocks under simulated mainnet conditions. Test results indicated stable fork execution and compatibility with existing L2 protocols such as Optimism and Arbitrum. Prior to Hoodi, the upgrade underwent two earlier testnets, elevated community review, and audit feedback integration. Stakeholders including client teams, staking providers, and research institutions participated in stress testing, ensuring broad support across the Ethereum ecosystem.
Implementation of Fusaka is expected to improve transaction throughput and lower fees, directly benefiting end users and developers. By reducing validator bandwidth costs, the upgrade may encourage new node operators to join, reinforcing decentralization. Ethereum Foundation researcher Alex Stokes commented, “Fusaka represents a key milestone in scaling efforts, delivering practical data availability enhancements that will underpin future protocol innovations.” Post-upgrade monitoring will focus on node performance metrics and cross-chain integration outcomes.
Looking forward, the protocol roadmap includes scheduled improvements for gas accounting and state expiry, with community input driving priorities. Fusaka’s activation will set the stage for 2026 research initiatives on sharding and advanced data sharding proposals. As the network approaches the scheduled date, ecosystem participants are urged to update clients, inspect testnet logs, and review documentation available on GitHub. This coordinated approach aims to minimize disruptions and maximize upgrade benefits.
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