The next major upgrade is Ethereum The network is already in front of you. The release, called Fusaka, short for “Fulu-OSAKA,” is scheduled for December 2025 and will combine significant changes in both Ethereum’s execution and consensus layers.
Fusaka traces several milestones for the Ethereum network following the 2022 merge. Shanghai/Shappera in 2023 introduced staked ETH withdrawals, Denkun in 2024 added protodunk sharding and blobs, and Pectra in 2025 brought validator flexibility and layer 2 interoperability.
According to the project roadmap, Fusaka is designed to expand data capacity, improve defenses against denial of service attacks, and introduce new tools for developers and users.
The changes are far-reaching. Fusaka is not a minor patch, but rather a redesign of how Ethereum manages data availability, blob pricing, and transaction safeguards. Its success will be measured by whether the network can scale to meet Layer 2 demands without burdening or disrupting node operators.
PeerDAS: Sample instead of saving everything
Fusaka’s core feature is PeerDAS (short for “Data Availability Sampling”), a new way to process BLOB data.
In Ethereum, BLOBs are temporary data packages introduced in proto-danksharding as part of the Dencun upgrade. BLOBs allow layer 2 rollups to cheaply post large amounts of transactional data to mainnet, increasing scalability without permanently bloating the blockchain state.
This provides redundancy, but creates a bottleneck as demand increases. The current model requires every full node on Ethereum to store every “blob” of layer 2 data posted to the chain.
PeerDAS changes the equation. Each node stores only a portion of the BLOB data (approximately one-eighth) and relies on cryptographic reconstruction to fill in the missing parts. This design relies on random sampling to verify data availability with an extremely low probability of error on the order of 1 in 10²⁰ to 1 in 10²⁴.
By distributing storage in this way, Ethereum could theoretically support up to 8x more blob throughput without requiring higher hardware or bandwidth from node operators. Rollups that rely on BLOBs to expose compressed transactional data are expected to benefit most directly.
BLOB economics and flexibility
Fusaka will also reimagine how BLOB data is priced and managed.
One of the key changes, EIP-7918, introduces blob reservation fees. Under current rules, BLOB prices can collapse near zero when execution gas fees become dominant. This creates an incentive for inefficient use. With reservation fees, there is always a baseline cost to use blobs, and layer 2 networks pay for the storage and bandwidth they consume.
Another mechanism, EIP-7892, introduces a BLOB parameter-only fork. These allow Ethereum clients to adjust their blob throughput outside of a complete hard fork. The goal is to allow developers to respond nimbly to unpredictable Layer 2 demands without waiting for the next scheduled upgrade.
protect from attack
Scaling up also means increasing Ethereum’s attack surface. Fusaka includes a set of changes to limit worst-case scenarios and protect your network from denial-of-service attacks.
- EIP-7823: Limits the input size for MODEXP operations to 8192 bits.
- EIP-7825: Sets the per-transaction gas cap to 2²⁴ units.
- EIP-7883: Increase gas cost for large exponents of MODEXP to better match computational complexity.
- EIP-7934: The maximum execution block size is 10 MB.
These changes reduce the risk that extreme transactions or excessive blocks can overload clients, stall propagation, or cause instability.
New tools for users and developers
Fusaka also aims to improve usability.
For users, EIP-7917 introduces pre-check support. This allows wallets and applications to look ahead to the proposer’s schedule, ensuring users know that their transactions will appear in the next block. The result is lower latency and less uncertainty about includes.
For developers, Fusaka adds two notable features.
- a CLZ opcode (counting leading zeros), helps with encryption routines and contract efficiency.
- EIP-7951provides native secp256r1 (P-256) signature verification. This is a common elliptic curve used in hardware devices and mobile systems, and its addition improves compatibility and account abstraction.
These changes are intended to reduce the burden on 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 to do anything. Your account balance, tokens, and applications will continue to function as before. Ethereum.org emphasizes that users must: Ignore scams asking you to “upgrade” or transfer ETH—There is no such requirement.
The onus is on validators and node operators to gradually upgrade their execution and consensus clients. Adjustment remains a delicate process. If validators get out of sync, you risk network downtime or a temporary chain break.
After a series of successful testnet activations, the Fusaka upgrade is scheduled to be introduced to Ethereum mainnet on December 3, 2025.
The future of Ethereum after Fusaka
Fusaka represents one of the boldest steps in Ethereum’s roadmap since the merger. This is an attempt to provide more blob capacity, stronger defenses, and new developer tools in one coordinated release.
Testing and development Net trials are underway, with client teams focused on PeerDAS’s performance, BLOB pricing model, and compatibility between execution and consensus software. If successful, Fusaka could mark a tipping point in Ethereum’s ability to scale towards the next wave of Layer 2 adoption.
