Ethereum’s Fusaka upgrade is the network’s next major hard fork, combining the Fulu consensus-layer update with the Osaka execution-layer update. According to Ethereum’s roadmap page and supporting explainers, Fusaka went live on December 3, 2025 after testnet activations on Holesky, Sepolia, and Hoodi, and it is positioned as the 17th major Ethereum upgrade following Pectra. The main technical change is PeerDAS (Peer Data Availability Sampling), which is designed to let Ethereum scale blob data more efficiently by allowing nodes to sample data instead of downloading and storing all of it. Ethereum describes this as the key feature that can expand blob space up to 8× current capacity, which should lower costs and improve throughput for rollups and other layer-2 systems that depend on Ethereum for data availability. Fusaka also raises Ethereum’s block gas limit and adds a per-transaction gas cap, changes intended to expand execution capacity while reducing congestion and improving network safety. The broader significance is that Fusaka advances Ethereum’s long-running scalability roadmap, especially the phase focused on rollups and data availability. It is also notable as a sign that Ethereum core developers are moving toward a faster hard-fork cadence, while the upgrade lays groundwork for later steps such as Glamsterdam and eventual parallel transaction processing.

AI-generated background, compiled from web sources — not editorial content.

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