Overview

• Core developers penciled in a Dec. 3, 2025 mainnet activation on the Sept. 17 All Core Developers’ Call, with final timing contingent on test results and reviews.
• Public testnets roll out in stages with Holesky on Oct. 1, Sepolia on Oct. 14, and Hoodi on Oct. 28 to rehearse the upgrade sequence.
• Blob capacity will rise via Blob Parameter Only forks, moving targets from 6/9 to 10/15 on Dec. 17 and to 14/21 on Jan. 7, 2026.
• A $2 million security contest on Sherlock runs Sept. 15–Oct. 13 to surface vulnerabilities before mainnet, with early submissions earning bonus multipliers.
• Fusaka includes data-availability enhancements such as PeerDAS and a broader set of EIPs, and the BPO approach avoids client updates to reduce fragmentation risk.