Ethereum’s ‘Fusaka’ Upgrade Clears Final Test; Mainnet Targeted for Early December
Alex Morgan
October 25, 2025
“Finishing Hoodi on schedule gives client teams the confidence to ship Fusaka without contingency windows,” said Marissa Lee, protocol lead at Prysmatic Labs.
What the Final Hoodi Test Proved
Ethereum core developers wrapped the final Hoodi testnet exercise for Fusaka overnight, executing cross-client attestations, blob transactions, and PeerDAS sampling without a hitch. The rehearsal was the last scheduled stress check before core devs propose a mainnet activation during the first week of December. Debug dashboards that flagged gossip delays in June stayed green for twelve consecutive epochs, a first for the multi-client test environment.
That stability, developers said on the AllCoreDevs call, means client teams can now focus on optimization and user education rather than firefighting. Besu and Nethermind maintainers confirmed no critical regressions surfaced, a marked contrast from the late-stage rewrites that delayed the Shanghai upgrade.
Upgrades Packed Into Fusaka
Fusaka bundles three headline changes: a 15% block gas target increase, a doubling of blob space for data availability, and the introduction of PeerDAS (EIP-7594) to distribute sampling duties among validators. PeerDAS, long requested by rollup teams, trims data availability costs by sharing verification responsibilities while keeping validator hardware requirements in check.
The upgrade also refreshes execution-layer fee markets with more predictable blob pricing, similar to the adjustments traders observed after recent ETF-driven congestion. Devs expect the blob and gas headroom to push average Layer 2 transaction fees below $0.02 during off-peak hours.
Mainnet Window and Next Steps
With testing milestones complete, coordinators are circulating a tentative mainnet activation slot between December 3 and December 6. The preference, according to ConsenSys engineer Parith Desai, is to target a Tuesday epoch to give staking providers a full business week for post-fork monitoring. Client teams will ship release candidates by November 15, and the next two AllCoreDevs calls will focus on upgrade communications for exchanges and node operators.
Ether’s price barely budged on the news, trading near $3,420, but derivatives desks reported a jump in calendar spread interest as traders positioned around the fork window. Market makers said flows mirrored the cautious buildup seen before recent leverage resets, suggesting participants want upside exposure without amplifying tail risk.
Impact Across the Ecosystem
Layer 2 operators greeted the milestone with plans to expand throughput ceilings the moment Fusaka lands. Optimism engineers said the upgrade should let them batch 25% more transactions per block while keeping sequencer fees stable. Starknet researchers, meanwhile, forecast a meaningful drop in proof publication costs because PeerDAS lowers redundancy for data commitments.
DeFi builders expect cheaper calldata to revive long-dormant strategies that require frequent state updates, from rebalancing vaults to on-chain derivatives hedging. Analysts warned that while Fusaka opens the door to higher volumes, it will also test validator preparedness, especially for smaller operators that need to tune gossip parameters before the fork.
What Builders Are Watching
Over the next month, client teams will focus on polishing documentation, releasing binaries, and coordinating with infrastructure partners. Education efforts already include walkthroughs for staking-as-a-service firms and updated runbooks for MEV relays. Tooling maintainers are refreshing integration tests to ensure PeerDAS metrics appear in dashboards on day one.
The hard fork’s success now hinges on validators installing releases promptly and dapp teams messaging users about temporary pauses during activation. Provided those steps land on schedule, Fusaka could usher in the biggest cost reset for rollups since proto-danksharding. Devs say they are already mapping follow-on research for 2026, including quantum-safe signature pilots that would build on Fusaka’s networking gains.