Ethereum Enters Final Testnet Phase Ahead of Fusaka Upgrade

Ethereum has entered the final testnet phase of its Fusaka upgrade ahead of its December 3 rollout. The highly anticipated hard fork features an improvement proposal that sets the gas fee limit for each transaction

The cap on individual transactions will improve block efficiency, reduce the risks of DoS, and create the groundwork for parallel execution in future upgrades

Ethereum Enters Final Testnet Phase

Ethereum has entered the final testnet phase of its Fusaka upgrade ahead of its expected mainnet rollout on December 3. The Fusaka upgrade introduces a per-transaction gas cap of 16.78 million units to enhance block efficiency and prepare the network for parallel execution. The change, already active on the Hokesky and Sepolia testnets, aims to prevent single transactions from using up the entire block’s gas. Previously, single transactions could use the full block gas limit of 45 million. This increased the risk of denial-of-service (DoS) attacks and limited scalability

A cap limits the processing power a single transaction can use and ensures a single transaction can’t monopolize the entire block. This allows the network to operate efficiently and handle activity evenly. The Ethereum Foundation discussed the upgrade in a blog post, stating,

“Previously, a single transaction could consume the entire block gas limit (~45 million gas), creating potential DoS risks and preventing parallel execution. EIP-7825 establishes a hard upper bound of 2²⁴ gas per transaction to improve block packing efficiency and pave the way for better parallel processing in future execution environments.”

The Ethereum Foundation advised users and developers relying on large transactions to ensure that their contracts and transaction builders align with the new cap. Ethereum Foundation researcher Toni Wahrstätter stated,

“For most users, nothing changes. The vast majority of transactions are already well below 16 million gas. However, certain contracts and deployment scripts, particularly those performing batch operations, may exceed this limit. Such transactions will be invalid once Fusaka activates.”

Transition Towards Parallel Execution

A per-transaction gas limit cap will help make block composition efficient and predictable, ensuring smaller transactions can fit within a block. The upgrade is part of Ethereum’s transition towards parallel execution. Parallel execution will allow Ethereum to process multiple transactions simultaneously. The introduction of transaction gas caps comes after Ethereum launched the Fusaka upgrade on the Sepolia testnet, raising the block gas limit from 45 million to 60 million. The Fusaka upgrade is scheduled to roll out on the Hoodi testnet on October 28, with the mainnet launch scheduled for December 2025

A Significant Upgrade

The Fusaka upgrade (EIP-7825) is a significant milestone for Ethereum. It comes after the Dencun upgrade (March 2024) and the Pectra upgrade (May 2025). Fusaka raises Ethereum’s default block gas limit from 45 million to 60 million, and sets a per-transaction gas cap of 16.77 million. It also introduces PeerDAS, the upgrade’s primary feature. PeerDAS (Peer Data Availability Sampling) enables Ethereum nodes to store only small, randomly selected portions of Layer 2 “blob” data, rather than the entire dataset. This reduces hardware demand and enables cheaper, higher-throughput scaling for Layer 2 networks while ensuring network security.

Glamsterdam, Ethereum’s next major upgrade, will focus on Ethereum’s execution layer and introduce EIP-7828, the first step towards parallel transaction processing. Gabriel Trintinalia, protocol engineer at Besu, stated,

“These testnets upgrades are crucial in building confidence ahead of the mainnet fork, allowing client teams, validators, and the ecosystem to validate performance, detect edge cases, and fine-tune parameters before activation.”

Disclaimer: This article is provided for informational purposes only. It is not offered or intended to be used as legal, tax, investment, financial, or other advice.