Ethereum Fusaka Upgrade Goes Live on Testnet Ahead of December Mainnet Launch

The Fusaka upgrade is now live on Ethereum’s Sepolia testnet, following its earlier activation on the Holesky testnet. The upgrade is designed to improve how the network handles transactions, performance, and data.

Right now, the focus is on testing the system under tougher conditions to get ready for the full mainnet launch in December. Users will not see big new features yet, but the upgrade strengthens the network for the future.

How is Fusaka Being Tested Now?

The Sepolia deployment is part of the three-step Fusaka roadmap. Developers are using it to test real-world conditions, focusing on the new data-availability system and higher block gas limits. Blocks are being tested at up to 60 million gas to allow more complex smart contracts and more transactions.

Gabriel Trintinalia, protocol engineer at Consensys’ Besu client, said the teams made careful preparations. “We made sure existing nodes, both hardware and network, can handle 60M gas blocks without causing problems”, he said. This helps the network grow while staying stable.

At the same time, Peer Data Availability Sampling, or PeerDAS, is being tested. It lets validators check transaction data by sampling small parts from multiple peers instead of downloading everything. This speeds up validation and reduces storage pressure, which is important for Ethereum’s long-term health.

What PeerDAS Does for Network Efficiency?

PeerDAS changes how Ethereum handles data. Validators no longer need to store all network data, which reduces the load on nodes and allows bigger blocks. Paul Harris, a Fusaka core developer at Consensys’ Teku client, said this could make scaling beyond previous limits possible.

With less data to store, the network can support more complex decentralized apps and higher transaction volumes while keeping decentralization. This could be especially important for DeFi, NFT platforms, and other high-traffic projects.

Testing PeerDAS now helps developers improve performance and find potential problems before the mainnet launch. Scaling a blockchain is not just about speed but also about keeping it reliable and easy to use.

Fusaka’s Place in Ethereum Upgrades

Ethereum’s Fusaka upgrade is the latest in a series of network improvements. It follows May’s Pectra upgrade, which added new account features and increased staking limits. Earlier upgrades, like The Merge in September 2022 and Dencun in March 2024, also brought big changes, from the move to proof-of-stake to lower gas fees.

The Shanghai upgrade in April 2023 allowed staked ETH to be withdrawn for the first time, an important step in Ethereum’s proof-of-stake journey. Fusaka builds on this, helping the network handle larger blocks and more complex transactions without overloading nodes.

The final testnet phase on Hoodi is set for later this month. Developers will fix any remaining issues before the December mainnet launch. These upgrades show Ethereum’s careful approach, focusing on security and reliability.

What to Expect When Fusaka Goes Live?

The testnet activations let developers and the community see how the network works in real conditions. Most users may not notice Fusaka right away, but the updates behind the scenes are important for Ethereum’s long-term health.

Bigger blocks, faster data, and less stress on nodes make the network stronger and more responsive. This upgrade improves Ethereum’s foundation and prepares it for higher demand and more advanced decentralized applications.