Ethereum activated its long-awaited “Fusaka” upgrade on Wednesday, marking the second major blockchain code change in 2025.
The update is designed to help Ethereum handle the increasingly large batches of transactions coming from the Layer 2 networks that sit on top of it.
The Fusaka update, also sometimes called a “hard fork,” went live at 21:49 UTC and is expected to finish in about 15 minutes, after which developers will know if the change was made without issue. Many of the core developers gathered to celebrate the occasion on the EthStaker livestream.
Fusaka, a combination of the names Fulu + Osaka, includes two hard forks on Ethereum that occur together: one at the consensus layer and one at the execution layer. The first is where transactions and smart contracts are executed, while the settlement layer is where these transactions are verified, finalized and secured.
At the center of the upgrade is PeerDAS, a system that allows validators to verify small portions of data rather than entire “blobs,” reducing both costs and computational burden for validators and Layer 2 networks.
Today, Layer 2s send their transaction data to Ethereum in the form of blobs, which validators must download and verify in their entirety. That process contributes to congestion and slows down the network. PeerDAS changes this by allowing validators to verify only a small portion of the blob data, speeding up the verification process and therefore reducing gas fees tied to processing.
Beyond Layer 2, the update is expected to lower the barrier for newer or smaller validator operators by reducing the resources required to run just a few validators. Still, Ethereum developers note that institutions that operate large fleets of nodes, such as staking pools, will not see the same level of savings.
“The improvements will take a few months to be fully implemented as we will only slowly increase the blobs to ensure the network can safely handle the increased throughput,” Marius Van Der Wijden, lead developer at the Ethereum Foundation, told CoinDesk via Telegram.
Ethereum developers acted quickly to release the update this year as the ecosystem faces a reputation for slow or delayed rollouts. The goal was to make a series of smaller improvements now while preparing for more ambitious changes in the future.
“The importance of PeerDAS was such that during the initial development of the Fusaka update, any features that carried a risk of delaying the fork, such as those that required more research or had high complexity, were deprioritized and removed from scope,” said Gabriel Trintinalia, Ethereum core developer and engineer at Consensys. Fusaka’s “update really shows that Ethereum is serious about making the Mainnet faster.”
Traditional financial institutions (TradFi) are also taking notice. Last month, Fidelity Digital Assets published a report describing Fusaka as a decisive step toward a more strategically aligned and economically coherent roadmap for Ethereum.
What else is there in Fusaka?
While Fusaka’s primary focus is PeerDAS, there are 12 other Ethereum Improvement Proposals (EIPs) that have been included in the package, primarily improving the developer experience and network health. These include:
- EIP-7642: Remove old, no longer used fields from Ethereum network messages to simplify and clean up the protocol.
- EIP-7823: Puts a maximum limit on the size of certain mathematical operations so that they do not overload the network.
- EIP-7825: Set an upper limit on the size of a single transaction so that no one can include extremely large and resource-intensive transactions.
- EIP-7883: Make a specific type of math operation more gas-intensive so that heavy calculations don’t unfairly strain the network.
- EIP-7892: Allows future updates to change only blob-related settings without touching the rest of the protocol, making blob tuning safer and easier.
- EIP-7910: Adds a new API method that allows software to easily check what configuration or rules a node is using.
- EIP-7917: Makes the process of predicting who will propose the next blocks more transparent and reliable.
- EIP-7918: Ensures that blob data rates remain aligned with the actual cost of processing them, avoiding extreme price fluctuations.
- EIP-7934: Add a hard size limit to certain block data to prevent overly large blocks from slowing down the chain.
- EIP-7935: Increase the default block gas limit to 60 million so that the network can perform more calculations on each block.
- EIP-7939: Adds a new simple instruction for smart contracts that allows them to improve the efficiency of some calculations.
- EIP-7951: Adds built-in support for a widely used cryptographic signature type.
As for what’s next, the developers are already looking at the network’s next big update, Glamsterdam, but nothing has been decided yet on when it will happen and what it will include.
Read more: Ethereum’s Fusaka upgrade could reduce node costs and make adoption easier
