Everything you need to know about the Ethereum Fusaka upgrade
Ethereum’s network is preparing for its next major upgrade called Fusaka, scheduled for December 3, 2025. As one of the most ambitious scaling and infrastructure improvements since The Merge, Fusaka is set to enhance Ethereum’s performance while laying the foundation for broader Layer-2 adoption and decentralized applications (dapps).
This article explains Fusaka’s core features, why it matters for the network and its stakers, and what actions are required to prepare.
What Is the Fusaka Upgrade?
Fusaka is designed to significantly increase Ethereum’s transaction capacity and improve how blockchain data is processed.
Key components include:
- Block Gas Limit Increase: The gas limit per block rises from 45 million to 150 million, allowing far more transactions and smart contract executions. This reduces congestion, lowers transaction fees, and creates room for greater network activity.
- Peer Data Availability Sampling (PeerDAS): Validators will no longer need to download entire large “blobs” of data. Instead, they can verify availability by sampling smaller pieces from multiple peers. This reduces hardware and bandwidth demands, enabling more participants to run nodes and helping Layer-2 rollups scale efficiently.
- Verkle Trees: A new cryptographic data structure compresses blockchain proofs into smaller, faster-to-verify components. Verkle Trees dramatically reduce storage requirements for nodes and make syncing more efficient, improving decentralization by lowering the barrier to operate a full node.
Why Fusaka Matters
Fusaka is more than a performance boost. It addresses several critical areas of Ethereum’s roadmap:
- Improved Network Efficiency: By expanding block capacity and lowering fees, Fusaka strengthens Layer-2 scaling and unlocks faster, cheaper user experiences on Ethereum.
- Support for Decentralization: With lighter node requirements from Verkle Trees and PeerDAS, more individuals can run validators and full nodes, increasing the network’s resilience.
- Enhanced Security: Fusaka includes Ethereum Improvement Proposals (EIPs) that balance larger block sizes with safeguards against denial-of-service (DoS) attacks. Gas recalibrations and block propagation improvements ensure the network remains stable as throughput grows.
- Economic Implications for Validators: More transactions and rollup activity mean increased execution activity and potentially more MEV opportunities, contributing to long-term staking rewards.
- Developer Experience: Smart contract execution and verification improvements provide developers with more efficient tools, accelerating the pace of innovation across the ecosystem.
- Roadmap Continuity: Fusaka builds on previous upgrades like Pectra and Dencun, pushing Ethereum closer to its long-term vision of full danksharding and handling tens of thousands of transactions per second.
Current Status and Testing
- Holesky and Sepolia Testnet Success: Fusaka has already been successfully deployed on both the Holesky (October 1) and Sepolia (October 14) testnets, with each network reporting smooth performance and no major issues. These deployments have validated the upgrade’s readiness under conditions closely simulating mainnet.
- Hoodi Testnet – Final Rehearsal: The final major testnet activation is scheduled for Hoodi on October 28, 2025. Hoodi has been engineered to closely mirror mainnet, providing one last comprehensive test of Fusaka’s stability and validator operations before the live rollout.
- Mainnet Launch Date:Once these final tests conclude successfully, Ethereum developers will finalize Fusaka’s mainnet activation date, currently targeted for December 3, 2025.
After Fusaka’s mainnet launch, the Holesky testnet will be retired as part of Ethereum’s ongoing network environment management.
What Should Stakers Do?
- No Action Needed for Delegated Stakers: stakefish is responsible for upgrading validator clients and maintaining uptime across the network. Delegators simply continue staking as usual.
- Validators Should Upgrade Promptly: For those running their own validator clients independently, it’s critical to update client software to support Fusaka to avoid penalties or missed rewards.
- Beware of Scams: No ETH tokens need manual upgrades or transfers. Any communication asking for token movement, private keys, or manual intervention with regard to Fusaka should be treated as fraudulent.
- Stay Informed: Follow stakefish’s communications and official Ethereum Foundation updates for the latest news and technical guidance.
Conclusion
The Fusaka upgrade is a foundational milestone for Ethereum’s scalability and decentralization. By expanding transaction capacity, reducing node requirements, and strengthening Layer-2 ecosystems, Fusaka ensures Ethereum can grow sustainably while maintaining security and accessibility.
For stakers, Fusaka means supporting a stronger, more efficient Ethereum network and benefiting from its long-term growth.
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Further Reading
- Fulu-Osaka (Fusaka) / Ethereum Foundation
- Fusaka Testnet Announcement / Ethereum Foundation
About stakefish
Founded in 2018 by Ethereum and Bitcoin veterans, stakefish is the leading validator for Proof of Stake blockchains. With support for 20+ networks, we combine institutional‑grade infrastructure with intuitive dashboards, transparent reporting, and a spotless slashing record so individuals and institutions alike can stake confidently while strengthening decentralized networks.
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