Context and Impact of Fusaka
Ethereum core developers have scheduled the Fusaka upgrade for December 3, 2025, a significant update aimed at addressing the network’s scalability challenges and reducing transaction costs for Layer-2 solutions. This hard fork introduces phased increases in blob capacity from the current 6/9 (target/maximum) to 10/15 blobs per block scheduled for December 17, 2025. Additionally, the gas limit per block will be raised from 45 million to 60 million initially, with plans to eventually reach 150 million in subsequent phases.
A key innovation in Fusaka is Peer Data Availability Sampling (PeerDAS), which enables nodes to verify data availability without downloading full datasets. This enhancement is expected to significantly reduce operational costs for rollups and improve throughput for decentralized applications. To ensure security, the Ethereum Foundation has allocated $2 million to a bug bounty program, and testnets (Sepolia and Hobi) will undergo updates in October before mainnet deployment. The Holesky testnet will be retired following Fusaka’s activation.
Implications and Risks
Fusaka’s improvements could transform Ethereum’s Layer-2 ecosystem by lowering fees and increasing transaction capacity, potentially boosting adoption of rollups and high-frequency dApps. These changes may also strengthen ETH’s value proposition, attracting greater institutional interest and ETF inflows. However, the upgrade carries operational risks: higher gas limits increase node complexity, requiring rigorous testing to prevent vulnerabilities. The exclusion of EIP-7907 highlights ongoing governance debates, reminding stakeholders that upgrade details may evolve until deployment.
For validators, rollup operators, and developers, Fusaka represents a critical step toward Ethereum’s scalability goals. Participants should monitor testnet results and official communications to prepare for technical adjustments. The success of Fusaka will depend on seamless execution and broader ecosystem adoption, with its impact on ETH’s price and network activity likely unfolding throughout 2026.
Key Points
-
Mainnet Activation: December 3, 2025
-
Blob Increase: December 17, 2025 (10/15 blobs per block)
-
Gas Limit: Raised to 60M initially, targeting 150M
-
Security: $2M bug bounty program
-
Testnets: Sepolia and Hobi updates in October; Holesky retirement post-Fusaka
In summary, Fusaka aims to solidify Ethereum’s competitive edge through enhanced scalability and cost efficiency. While the upgrade promises long-term benefits, stakeholders should remain vigilant about technical execution and market dynamics during this transition.
