Ethereum Fusaka Hard Fork Set for December with Double Blob Capacity

TLDR

• Ethereum’s Fusaka upgrade will launch on December 3, introducing 12 EIPs for scalability.
• The Fusaka upgrade will gradually increase blob capacity to improve layer-2 efficiency.
• A $2M audit program will secure Fusaka’s code before the mainnet deployment.
• Ethereum’s validator exit queue has hit an all-time high, raising concerns about market impact.

Ethereum’s upcoming Fusaka upgrade has been officially rescheduled to launch on December 3, 2025. The delay, which was agreed upon by Ethereum’s core developers, ensures that security and scalability take priority. The Fusaka upgrade is expected to introduce twelve Ethereum Improvement Proposals (EIPs) that aim to enhance Ethereum’s overall performance and user experience.

Fusaka’s deployment will be accompanied by several key improvements, including a doubling of blob capacity, set to begin two weeks after the upgrade on December 17. This increase will continue in January 2026 with an additional hard fork, pushing the capacity to handle more blobs, which are critical for scaling layer-2 solutions.

Blobs and Layer-2 Scaling

Blobs, introduced in the Dencun upgrade earlier in 2024, allow Ethereum to store large data sets off-chain. This significantly reduces the costs and increases the efficiency of transactions on layer-2 networks like rollups.

The upcoming Fusaka upgrade will feature an increase in blob capacity, from a current maximum of six to 15 blobs per block in December 2025, followed by a further increase to 21 blobs per block in January 2026.

The Blob Parameter Only (BPO) hard forks will enable Ethereum to scale efficiently without requiring client-side updates. This approach ensures smooth deployment with minimal risk of network fragmentation. Ethereum developer community ethPandaOps emphasized that these BPOs would allow the mainnet to scale considerably in a secure manner.

Public Testing and Audit Program

Before Fusaka’s official launch, three public testnets will run between October and November 2025. These tests are essential for identifying potential vulnerabilities and ensuring the upgrade’s stability.

Ethereum’s focus on security is also reflected in the $2 million audit program initiated by the Ethereum Foundation, which rewards developers for finding and disclosing vulnerabilities in Fusaka’s code.

The foundation’s decision to allocate substantial funds for security audits reflects the increasing emphasis on making sure that the upgrade runs smoothly. The rigorous testing process will aim to address any issues before the upgrade is deployed on the Ethereum mainnet.

Impact of Fusaka on Ethereum’s Ecosystem

Fusaka is part of Ethereum’s broader roadmap to improve network efficiency and scalability. It follows the successful Pectra upgrade in May 2025, which improved validator staking limits and account abstraction. Fusaka’s implementation will play a vital role in enhancing Ethereum’s infrastructure to support growing decentralized applications (dApps) and layer-2 solutions.

While Fusaka’s blob capacity increase is a notable improvement, the network still faces challenges related to its validator exit queue. Ethereum’s exit queue has reached an all-time high, with over 2.6 million ETH waiting to be unstaked. This large number of unstaked ETH, worth $12 billion, has raised concerns among some in the Ethereum community about potential selling pressure and its impact on ETH’s price.

Ethereum co-founder Vitalik Buterin defended the long exit queue, emphasizing its role in ensuring the network’s security. He argued that reducing the wait times could compromise the robustness and trustworthiness of the Ethereum protocol.

Ethereum’s Continued Evolution

Ethereum’s Fusaka upgrade is a critical step in the network’s evolution, aiming to position it as a more scalable and secure platform for decentralized applications.

As the Ethereum community looks toward its future upgrades, including the Glamsterdam hard fork expected in 2026, the focus will remain on improving the network’s performance while maintaining decentralization and security.

The success of Fusaka and its associated hard forks will mark a significant milestone in Ethereum’s long-term journey toward becoming a more efficient and user-friendly blockchain. The upcoming months will be crucial as developers finalize the code and test the upgrade, ensuring that it meets the high standards set by the Ethereum community.

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