Ethereum Fusaka upgrade, Scheduled for the second half of this year

Tim Beiko notifying that EOF is removed from Pusaka upgrade (Source: @TimBeiko, X)

The upcoming network upgrade of Ethereum, the Pusaka hard fork, is expected to take place in the third or fourth quarter of 2025. Thomas Kajetan Stanczak, co-director of the Ethereum Foundation, stated, "We are preparing for the Pusaka network upgrade, but the specific timetable has not been confirmed yet."

This hard fork was to include the EOF (EVM Object Format) upgrade for improving the structure of the Ethereum Virtual Machine (EVM), but its application was ultimately excluded. Core Ethereum developer Tim Beiko said through his X account and a GitHub post, "EOF has been excluded from the Pusaka upgrade," explaining that "due to technical uncertainties and concerns about schedule delays, developers decided not to adopt it."

EOF was a plan to structure smart contract bytecode to verify it only once at the time of deployment, and to separate code from data for increased processing efficiency. It was expected to play an important role in future scalability and security improvements by incorporating various Ethereum Improvement Proposals (EIP), but concerns were also raised about system complexity increase and the potential emergence of new vulnerabilities.

Ethereum developer Pascal Kaversaccio criticized, "EOF is excessively complex, and the burden of maintaining existing EVM is significant." He also pointed out that adopting EOF would require upgrading various development tools and could lead to unforeseen security issues.