Fusaka follows this 12 months’s Pectra upgrade, representing a significant step ahead in Ethereum’s scaling roadmap by introducing PeerDAS and key enhancements that improve blob throughput, L1 efficiency, and consumer expertise.
This submit proclaims the testnet activation schedule for the primary three testnets, starting with Holesky at slot 5,283,840 (October 1, 2025, 08:48:00 UTC). See the activation table under for the whole Sepolia and Hoodi timeline. Fusaka additionally introduces Blob Parameter Solely (BPO) forks to securely scale blob throughput after PeerDAS activation. These are minimal, config-only upgrades that alter the blob goal/max and price replace fraction.
The Fusaka testnet shopper releases are listed below. As soon as all three testnets have efficiently upgraded, a mainnet activation slot might be chosen.
Fusaka Overview
Fusaka’s headlining EIP is PeerDAS (Peer Information Availability Sampling), which permits vital blob throughput scaling. The improve additionally consists of optimizations throughout execution and consensus layers to scale L1 efficiency and enhance consumer expertise. This submit outlines the main enhancements. For a extra complete overview, see ethereum.org’s guide to the upgrade.
Scale Blobs: PeerDAS
EIP-7594 introduces PeerDAS, a brand new networking protocol that permits nodes to confirm blob information availability by way of sampling somewhat than downloading full blobs. It is a key step towards scaling blob throughput whereas sustaining Ethereum’s safety and decentralization.
For the reason that Dencun upgrade, layer 2 utilization has grown considerably, usually reaching the present 9 blob per block restrict. PeerDAS permits Ethereum to extend this restrict with out compromising on safety. It does so by utilizing erasure coding to permit nodes to pattern parts of blob information whereas nonetheless cryptographically guaranteeing that the complete information is obtainable throughout the community. This creates a path towards larger blob targets outlined in Ethereum’s scaling roadmap.
This sampling strategy instantly advantages layer 2 rollups by supporting larger blob throughput with out proportionally growing bandwidth necessities for particular person nodes. As blob capability scales past present limits, L2 transaction charges can lower additional whereas sustaining the safety ensures of knowledge availability on Ethereum L1.
To soundly ramp blob throughput after PeerDAS is activated, Ethereum will use Blob-Parameter-Solely (BPO) forks. Fusaka consists of two deliberate BPO parameter changes on Holesky beginning October 7, 2025, with related schedules for different testnets. These BPOs will elevate the per-block blob goal and most from 6 & 9 respectively to 10 & 15 in BPO1 and 14 & 21 in BPO2.
Scale L1
ModExp Optimization
EIP-7883 and EIP-7823 work collectively to optimize the ModExp precompile. EIP-7883 will increase fuel prices to extra precisely mirror computational complexity, together with elevating minimal fuel prices and tripling normal value calculations. EIP-7823 units higher bounds for ModExp operations. Collectively, these adjustments make sure that resource-intensive cryptographic operations are correctly priced and assist potential future block fuel restrict will increase.
Transaction Fuel Restrict Cap
EIP-7825 implements a protocol-level transaction fuel restrict cap of 16,777,216 fuel, stopping particular person transactions from consuming extreme block fuel and defending in opposition to DoS assaults. This lays the groundwork for parallel transaction processing within the EVM.
Community Protocol Optimization
EIP-7642 introduces eth/69, which removes pre-merge fields and the receipt Bloom from the networking protocol. This cleanup reduces sync bandwidth necessities, provides an express historical past serving window for nodes to promote and simplifies the codebase by eradicating legacy elements which might be not wanted post-merge.
Fuel Restrict Enhance
EIP-7935 raises Ethereum’s default fuel restrict to 60MM, reflecting the fuel restrict that core builders imagine Ethereum L1 can safely scale to. This enhance permits extra L1 execution capability and has been totally examined throughout completely different shopper mixtures to make sure community stability and safety.
Past these efficiency enhancements, Fusaka additionally enhances the consumer and developer expertise with a number of focused upgrades.
Enhance UX
secp256r1 Precompile
EIP-7951 provides native assist for the secp256r1 elliptic curve by way of a brand new precompiled contract. This allows direct integration with fashionable safe {hardware} like Apple Safe Enclave, Android Keystore, and FIDO2/WebAuthn gadgets, decreasing friction for mainstream blockchain adoption by way of acquainted authentication flows.
Rely Main Zeros Opcode
EIP-7939 introduces the CLZ (Rely Main Zeros) opcode, offering a local, gas-efficient option to carry out basic bit-counting operations. This addition helps mathematical operations, compression algorithms, and post-quantum signature schemes whereas decreasing ZK proving prices.
Fusaka Specs
The whole listing of adjustments launched in Fusaka will be present in EIP-7607. The core EIPs embrace:
Extra supporting EIPs:
Full specs for the execution and consensus layer adjustments can be found within the following releases:
Fusaka additionally introduces adjustments to the Engine API used for communication between consensus and execution layer nodes. These are specified within the osaka file of the execution-apis repository.
Fusaka Safety
Safety researchers can take part within the Fusaka audit competition to assist establish potential points earlier than mainnet deployment.
Fusaka Activation
The Fusaka community improve will activate on Holesky, Sepolia, and Hoodi testnets as follows:
| Community | Slot | UTC Time | UNIX Timestamp |
|---|---|---|---|
| Holesky | 5,283,840 | 2025-10-01 08:48:00 | 1759308480 |
| Sepolia | 8,724,480 | 2025-10-14 07:36:00 | 1760427360 |
| Hoodi | 1,622,016 | 2025-10-28 18:53:12 | 1761677592 |
As previously announced, word that Fusaka would be the final community improve deployed to Holesky. It will likely be shut down shortly after the improve has been deployed on it.
Blob Parameter Solely (BPO) Fork Schedule
Following the primary Fusaka activation, the community will implement Blob Parameter Solely forks to progressively enhance blob throughput. BPO1 will enhance the per-block blob goal and most to 10 & 15 respectively. BPO2 will additional enhance the goal to 14 and most to 21.
Holesky BPO Schedule
| BPO Fork | Epoch | Date & Time (UTC) | Unix Timestamp |
|---|---|---|---|
| BPO1 | 166,400 | 2025-10-07 01:20:00 | 1759800000 |
| BPO2 | 167,936 | 2025-10-13 21:10:24 | 1760389824 |
Sepolia BPO Schedule
| BPO Fork | Epoch | Date & Time (UTC) | Unix Timestamp |
|---|---|---|---|
| BPO1 | 274,176 | 2025-10-21 03:26:24 | 1761017184 |
| BPO2 | 275,712 | 2025-10-27 23:16:48 | 1761607008 |
Hoodi BPO Schedule
| BPO Fork | Epoch | Date & Time (UTC) | Unix Timestamp |
|---|---|---|---|
| BPO1 | 52,480 | 2025-11-05 18:02:00 | 1762365720 |
| BPO2 | 54,016 | 2025-11-12 13:52:24 | 1762955544 |
Shopper Releases
The next shopper releases are appropriate for the Fusaka improve on all three testnets. Additional variations will activate assist on mainnet. As soon as these are launched, one other announcement might be made on this weblog.
Consensus Layer Holesky, Sepolia & Hoodi Releases
When working a validator, each the Consensus Layer Beacon Node and Validator Shopper should be up to date.
Be aware: Lodestar customers ought to all the time use the newest rc model listed on their releases page.
Execution Layer Holesky, Sepolia & Hoodi Releases
FAQ
How do Ethereum community upgrades work?
Ethereum community upgrades require express opt-in from node operators on the community. Whereas shopper builders come to consensus on what EIPs are included in an improve, they don’t seem to be the last word deciders of its adoption.
For the improve to go reside, validators and non-staking nodes should manually replace their software program to assist the protocol adjustments being launched.
In the event that they use an Ethereum shopper that isn’t up to date to the newest model (listed above), on the fork block, it should disconnect from upgraded friends, resulting in a fork on the community. On this state of affairs, every subset of the community nodes will solely keep related with those that share their (un)upgraded standing.
Whereas most Ethereum upgrades are non-contentious and circumstances resulting in forks have been uncommon, the choice for node operators to coordinate on whether or not to assist an improve or not is a key function of Ethereum’s governance.
For a extra exhaustive overview of Ethereum’s governance course of, see this talk by Tim Beiko.
As an Ethereum mainnet consumer or ETH holder, is there something I must do?
Briefly, no.
This announcement solely pertains to Ethereum testnets. An additional announcement might be made for Fusaka’s activation on the Ethereum mainnet, however even then, Ethereum mainnet customers and ETH holders should not anticipated to must take motion.
As a non-staking testnet node operator, what do I must do?
To be appropriate with the improve on any of those testnets, replace your node’s execution and consensus layer shoppers to the variations listed within the desk above.
As a testnet staker, what do I must do?
To be appropriate with the improve on any of those testnets, replace your node’s execution and consensus layer shoppers to the variations listed within the desk above. Ensure each your beacon node and validator shopper are up to date.
As a non-testnet node operator or staker, what do I must do?
Nothing for now. Additional bulletins might be made for Fusaka’s activation on mainnet.
As an software or tooling developer, what ought to I do?
Evaluation the EIPs included in Fusaka to find out if and the way they have an effect on your challenge. The introduction of PeerDAS, secp256r1 assist, and the brand new CLZ opcode provide thrilling alternatives for enhanced performance and efficiency optimizations.
Why “Fusaka”?
Upgrades to the execution layer comply with Devcon metropolis names, and people to the consensus layer use star names. “Fusaka” is the mixture of Fulu, a star within the constellation of Cassiopeia, and Osaka, the placement of Devcon V.
