Ethereum Fusaka Upgrade Set for December 3: Key Features and Testnet Schedule Revealed  

The Ethereum Fusaka upgrade is tentatively scheduled for mainnet launch on December 3, 2025, following testnet activations starting October 1. This update aims to enhance scalability with features like Peer Data Availability Sampling, doubled blob capacity, increased block gas limit to 150 million, Verkle Trees for optimized storage, and EVM improvements. Developers will reconfirm dates soon, with blob capacity doubling two weeks post-activation. A $2 million audit contest is underway to identify bugs. In a $3.5 trillion cryptocurrency market, the Ethereum Fusaka upgrade builds on previous enhancements, paving the way for Glamsterdam in 2026. This article covers the timeline, features, technicals, audit, and implications.

Upgrade Timeline

The Ethereum Fusaka upgrade rollout begins with testnets: Holesky on October 1, Sepolia on October 14, and Hoodi on October 28. Mainnet activation is targeted for December 3, with exact epochs and times to be finalized. This phased approach ensures thorough testing, similar to past upgrades. The Ethereum Fusaka upgrade follows a developer call where timelines were discussed, emphasizing stability before launch.

• Holesky: October 1.
• Sepolia: October 14.
• Hoodi: October 28.
• Mainnet: December 3.

Key Features of Fusaka

The Ethereum Fusaka upgrade introduces Peer Data Availability Sampling, allowing validators to verify large blobs by sampling small portions from peers, reducing data load. Blob capacity will double two weeks after activation, enhancing scalability. Other elements include Verkle Trees for smaller proof sizes and optimized storage, plus EVM performance boosts for faster smart contract execution.

• Peer DAS: Efficient blob verification.
• Blob increase: Doubles post-activation.
• Verkle Trees: Optimized data storage.

Technical Enhancements

The Ethereum Fusaka upgrade raises the block gas limit from 30 million to 150 million, supporting more transactions per block. This aligns with Ethereum's goal of maintaining decentralization while scaling. The upgrade focuses on security and efficiency, building on prior forks without major disruptions.

• Gas limit: 150 million units.
• EVM: Faster execution.
• Focus: Scalability and security.

Audit and Security Measures

The Ethereum Foundation launched a four-week audit contest for the Ethereum Fusaka upgrade, offering up to $2 million in rewards for bug discoveries. This proactive step ensures robustness before mainnet, addressing potential vulnerabilities in features like Peer DAS and Verkle Trees.

• Contest value: Up to $2 million.
• Duration: Four weeks.
• Goal: Pre-mainnet bug fixes.

Next Steps and Glamsterdam

Post-Fusaka, the Ethereum Fusaka upgrade paves the way for Glamsterdam in 2026, introducing full EVM Object Format (EOF) and faster block times. Developers urge dialing back Glamsterdam discussions to focus on Fusaka's smooth rollout.

• Glamsterdam: 2026, EOF and block time improvements.
• Developer advice: Prioritize Fusaka.

Final Insights

The Ethereum Fusaka upgrade, set for December 3, 2025, enhances scalability with Peer DAS, doubled blobs, and Verkle Trees, backed by a $2 million audit. In a $3.5 trillion market, it positions Ethereum for growth. For tips, monitor testnet activations for progress and explore developer calls for details. Track Ethereum metrics post-upgrade for performance insights.