Ethereum Sets December 3 for Fusaka Hard Fork Launch

Key Highlights

• Fusaka upgrade goes live on Ethereum mainnet on December 3, 2025
• Testnets include Holesky, Sepolia, and Hoodi with phased blob increases
• Ethereum Foundation launches $2M Sherlock audit competition before release

Testnet Rollouts and Network Enhancements Highlight the Upgrade

Ethereum developers have confirmed the Fusaka upgrade launch schedule, set to go live on the mainnet on December 3, 2025, following a series of testnet deployments. Analyst Christine Kim shared the update after the weekly All Core Developers Consensus (ACDC) call #165.

Important decisions were made during the call, including the public testnet launch and the BPO hard fork schedule. According to the plan, the Fusaka rollout will proceed as follows:

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

Additionally, blob capacity will increase in two stages after Fusaka activation:

• First week: from 6/9 to 10/15
• Second week: up to 14/21

Fusaka will follow the Pectra hard fork, which successfully activated on May 7, 2025, including 11 Ethereum Improvement Proposals (EIPs) and described as the largest deployment since the Merge.

Ethereum Foundation Preparations

The Ethereum Foundation is actively preparing for Fusaka’s release. On September 15, it announced an auditing competition on the Sherlock platform with a $2 million prize pool to identify code vulnerabilities before the mainnet launch. The four-week competition aims to ensure the upgrade is secure and reliable.

At the same time, changes to testnet infrastructure continue. Holesky will be deprecated two weeks after Fusaka installation due to technical challenges during the Pectra deployment.

Fusaka is expected to enhance network scalability, and the gradual increase in blob throughput will lay the foundation for future upgrades, including Glamsterdam, already planned for 2026.