What to expect from Ethereum's Fusaka Hard Fork

The next big upgrade to Ethereum, Fusaka, is set to launch in November with an emphasis on behind the scenes' performance and security improvements, rather than adding new features to users.

Ethereum's next protocol upgrade, Fusaka, will enter the final testing and planning stages upon activation of the mainnet, which is scheduled for tentatively in early November 2025.

Arrived about six months after the Pectra Hard Fork, Fusaka continues to accelerate Ethereum upgrade cadence, focusing on behind-the-scenes improvements aimed at improving performance, scalability and node resilience, particularly for client developers and infrastructure providers.

Unlike Pectra, which offers user-friendly features such as account abstraction and higher validator restrictions, Fusaka does not change the behavior of smart contracts. Instead, it bundles 11 Ethereum improvement proposals that improve core protocol parameters, improve security and optimize gas efficiency.

Who suggests and why

One of the key suggestions, EIP-7825, can help protect your nodes from being overwhelmed by spam or harmful messages. Another major change in the table is increasing the block gas limit to 150 million. This could potentially fit more transactions into each block, but it also comes with trade-offs such as more block spread and more burden on the data storage of the network.

The EIP-7907 was intended to double the contract code size limit and introduce new gas metering rules, but was eventually removed to avoid testing delays. It could be revisited on a future fork.

Nixo, an Ethereum Protocol Support member, urged the team to stick to a strict timetable so that Fusaka lands before the leading developer conference DevConnect highlights the importance of timely client releases next month and half.

What's in the box

This is a bite-sized look of some of the headline features that Fusaka brings.

• Higher gas limits. The block gas limit could be increased to 150 million units, and each block could contain more transactions. This will reduce fees and focus on speeding up the network.
• Security Boost (EIP ‑ 7825). New checks to protect certain attack patterns, make nodes more robust and reduce the risk of network destruction.
• Code size and weight adjustment. The EIP ‑ 7907, which doubles the code size limit and adds a new gas fee, was pulled for speed testing, but future forks could revisit it.

Overall, these changes do not significantly affect how most smart contracts work. Instead, it helps your network handle more traffic in a safer and more efficient way.

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How did you get here?

Ethereum follows an upgrade cycle of approximately six months. The last major fork, Pectra, was released in May and brought features like account abstraction and higher staking restrictions. Shortly after Pectra's release, discussion began about the next step, and Fusaka had reached the top of the list by mid-2025.

Behind the scenes, Ethereum's Allcoredevs Meetings, a regular gathering of protocol teams, discussed which EIPs would bundle. On August 1st, the final set of Fusaka's EIPs is confirmed, frozen and the client team will give them a month or two to make changes. The upgrade path for Ethereum in Fusaka would look like this:

1. Start devnet. The first developer was released in mid-July 2025, allowing researchers and node software teams to test new code in a controlled setting.
2. Public Test Net. Two public testnets are scheduled for late September and October 2025, opening the door to wider community testing and bug hunting.
3. Mainnet hard fork. Apart from a major setback, Fusaka will ideally be revitalized at the Ethereum Mainnet in early November, prior to the DevConnect meeting in Buenos Aires (November 17-22).

Once everything goes smoothly, the developers will tally the testnet results in November and deploy the upgrades at pre-announced block heights, ensuring that all nodes are upgraded together.

In the long run, users will remain on a fast, inexpensive and secure blockchain. Fusaka isn't a major overhaul, but it's a meaningful step to help Ethereum stay competitive with faster chains and Layer 2. By increasing your capabilities and strengthening your defenses, your network can be more welcoming to Defi apps, games and other use cases.

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