Ethereum’s upcoming Fusaka hard fork, set to go live on December 3, 2025, aims to significantly expand data capacity and make the network faster and more efficient.
Key Takeaways
- Fusaka upgrade activates on December 3, 2025, beginning with three public testnets starting October 1.
- Blob capacity will more than double through two Blob Parameter Only (BPO) hard forks following the main upgrade.
- PeerDAS will reduce bandwidth needs and enhance Layer 2 scalability, improving transaction efficiency.
- Ethereum’s exit queue hits all-time high, reflecting shifting validator dynamics ahead of the upgrade.
What Happened?
Ethereum developers have finalized plans to launch the long-anticipated Fusaka hard fork on December 3, 2025, targeting backend improvements to make the network more scalable and resource-efficient. The upgrade follows the Pectra and Dencun updates and continues Ethereum’s push for higher transaction throughput with lower costs.
Important decisions were made on today’s Ethereum developer call, ACDC #165. Developers confirmed the public testnet schedule and BPO hard fork schedule for Fusaka.
— Christine D. Kim (@christine_dkim) September 18, 2025
Let’s get into it. pic.twitter.com/mNrYMYyDj2
Fusaka’s Core Goals: Efficiency, Scalability, No Client-Side Changes
Fusaka is a non-user-facing upgrade that focuses on Ethereum’s infrastructure. The upgrade will introduce around 11 to 12 Ethereum Improvement Proposals (EIPs) designed to reduce bandwidth and storage requirements, increase data availability, and strengthen support for Layer 2 rollups.
A central feature is the integration of PeerDAS (Peer Data Availability Sampling) via EIP-7594, which allows validators to verify data without downloading entire data blobs. Instead, they can sample smaller segments, cutting resource usage and boosting scalability.
Blob Capacity Expansion: Two Key BPO Forks
Though Fusaka officially launches on December 3, blob capacity changes will roll out in stages. Two critical Blob Parameter Only (BPO) forks will follow:
- BPO1 (around December 17): Increases blob count limits from 6/9 (target/max) to 10/15.
- BPO2 (around January 7, 2026): Further expands blob capacity to 14/21, effectively more than doubling current limits.
According to developer group ethPandaOps, five total BPOs are planned to ensure gradual and safe scaling of the network. These parameter-only forks will not require client-side updates, simplifying deployment.
Blobs store large offchain data sets that enable Layer 2 solutions to operate more efficiently. The upgrade is expected to support throughput of up to 12,000 transactions per second by 2026, driven by broader gas limit discussions and EIPs like EIP-7935 and EIP-9698, which aim to dramatically increase transaction capacity.
Security Comes First: Ethereum Foundation Offers $2M Bug Bounty
To ensure the robustness of the Fusaka upgrade, the Ethereum Foundation launched a four-week audit campaign offering up to $2 million in rewards for discovering vulnerabilities in the Fusaka codebase.
This move highlights the network’s commitment to stability as it pursues major protocol enhancements.
Market and Validator Dynamics: Exit Queue Reaches Record High
Meanwhile, Ethereum’s validator ecosystem is undergoing notable changes. Over 2.6 million ETH (valued at $12 billion) entered the exit queue last week, marking an all-time high. This surge comes as staking participation slows, with fewer validators entering the pool amid concerns over potential sell pressure.
The current exit queue has a wait time of 43 days, triggering community debate. Ethereum co-founder Vitalik Buterin defended the lengthy queue, stating that reducing it would make the protocol “much less trustworthy”.
CoinLaw’s Takeaway
In my experience covering Ethereum upgrades, Fusaka might be one of the most technically important updates since The Merge. While it doesn’t offer flashy new features for end users, its deep improvements to data handling and validator efficiency are vital to scaling the network responsibly.
I found the staggered rollout of blob capacity, especially through BPO forks, a smart move. It allows Ethereum to scale methodically without risking network instability. Also, the $2 million audit bounty is a clear sign that security is not being sacrificed for speed. For developers and investors, this upgrade could significantly improve the network’s performance and lower transaction costs in 2026.
