Next major upgrades Ethereum The network is on the horizon. It is called Fusaka, known as the short “Fulu-osaka”. This release is scheduled for the fourth quarter of 2025 and combines significant changes in both the Ethereum execution and consensus layers.
Fusaka will follow several milestones in the Ethereum network following the 2022 merge. In 2023, Shapella was introduced by Dencun in 2024 with Proto-Danksharding and Blobs, and in 2025 with Pectra.
According to the project’s roadmap, Fusaka is designed to increase data capacity, enhance defense against denial-of-service attacks, and introduce new tools for developers and users.
The changes have been wiped out. Fusaka is not a minor patch, but a redesign of how Ethereum manages data availability, blob pricing, and transaction safeguards. Its success is measured by whether the network can scale to meet rising Layer 2 demands without destroying or overburdening the node operator.
Peerdas: Sampling instead of saving everything
A central feature of Fusaka is Peerdas, short for “data availability sampling,” a new way of processing BLOB data.
In Ethereum, BLOB is a temporary data package introduced with Proto-Danksharding as part of a Dencun upgrade. Blobs allow layer-2 rollups to post large amounts of transactional data cheaply to the mainnet, increasing scalability without ever inflated blockchain state.
This ensures redundancy, but creates bottlenecks as demand increases. In the current model, every full node in Ethereum must store all “blobs” of Layer 2 data posted to the chain.
Peerdas changes the equation. Each node stores only a small portion (one eighth) of the blob data and relies on encryption reconstruction to fill in missing pieces. This design relies on random sampling to verify data availability with very low error probability in order from 10² to 10².
By distributing storage this way, Ethereum can theoretically support up to eight times the blob throughput without requiring higher hardware or bandwidth from node operators. Rollups that rely on blobs to expose compressed transactional data are expected to be the most direct benefit.
Blobs’ economy and flexibility
Fusaka will also restructure how you price and manage your BLOB data.
One of the key changes, EIP-7918, introduces Blobs reserve fees. Under current rules, if the running gas rate controls, the blob price can approach zero. This creates an incentive for inefficient use. The reserve fee ensures that BLOB usage always has a baseline cost, paying for the storage and bandwidth consumed by the Layer 2 network.
Another mechanism, EIP-7892, introduces a fork that only has BLOB parameters. These allow Ethereum clients to adjust their blob throughput outside the full hard fork. The goal is to provide developers with agility to meet unpredictable Layer 2 demands without waiting for the next scheduled upgrade.
Security against attacks
Scale-up means increasing the attack surface of Ethereum. Fusaka includes a set of changes to limit worst-case scenarios and protect your network from denial of service attacks.
- EIP-7823: Cap input size for ModExp operations in 8192 bits.
- EIP-7825: Set the gas cap for each transport to 2²⁴ units.
- EIP-7883: Increases the gas costs of large indexes in ModExp to better match your calculation efforts.
- EIP-7934: Cap execution block size of 10 MB.
Together, these changes reduce the risk that extreme transactions or oversized blocks can overload clients, stop propagation, or cause instability.
New tools for users and developers
Fusaka also aims to improve ease of use.
For users, the EIP-7917 will introduce pre-registration support. This allows wallets and applications to look ahead on the proposal schedule and allow users to lock transactions from being displayed in future blocks. As a result, there is less potential and less uncertainty about inclusion.
For developers, Fusaka adds two notable features:
- a CLZ Opcode (zero count reading), helps in encryption routines and contract efficiency.
- EIP-7951provides signature verification for native SECP256R1 (P-256). This is a common elliptic curve used in hardware devices and mobile systems, and the addition of this increases compatibility and account abstraction.
These changes aim to reduce friction for application developers and pave the way for new wallet designs and security models.
What ETH holders need to know
For everyday Ethereum users, Fusaka doesn’t need action. Account balances, tokens, and applications will continue to function as before. ethereum.org emphasizes what users should do Ignore scams that ask you to “upgrade” your ETH or transfer funds– There are no such requirements.
The responsibility lies with the validators and node operators, and they must upgrade the running and consensus clients step by step. The adjustment remains a delicate process. If the validators become out of sync, the network risks downtime or temporary chain splitting.
Fusaka will be active on Ethereum’s Holeski Testnet on October 1st, with Sepolia on October 14th, Hoodie and Mainnet on October 28th on December 3rd.
At a high level, what developers agree on should be a schedule for Fusaka to move forward.
October 1st: Holesky Upgrade
October 14th: Sepolia upgrade
October 28th: Hoodie Upgrade
December 3rd: Mainnet upgrade– Christine D. Kim (@christine_dkim) September 18, 2025
The future of Ethereum after Fusaka
Fusaka represents one of the boldest steps on Ethereum’s roadmap since the merge. This is an attempt to provide more blob capacity, tighter defense, and new developer tools in a single tuned release.
Testing and DevNet exams are ongoing, with client teams focusing on Peerdas performance, Blob Pricing model, and compatibility across execution and consensus software. If successful, Fusaka can mark a turning point in Ethereum’s ability to expand towards the next wave of Layer 2 adoption.
