Ethereum’s development team has tentatively scheduled the activation of the much-awaited Fusaka upgrade on the main network for December 3rd.
The proposed timeline, detailed in a preliminary plan discussed during the All Core Developers’ Call (ACDC) on September 17th, is still subject to change. However, it indicates increasing progress towards a major technical advancement for Ethereum.
The implementation will proceed in stages, starting with test networks. Holesky is slated for an upgrade on October 1st, followed by Sepolia on October 14th, and Hoodi on October 28th. If these test runs are successful, the modifications will be deployed to the Ethereum mainnet in December.
Staged Blob Implementations
Christine Kim, formerly a research vice president at Galaxy Digital, pointed out that the developers will continue to refine the specific dates, epochs, and timing in the coming weeks.
She also noted:
“Based on initial assessments of Fusaka Devnet-5, the capacity for blobs is expected to more than double in the two weeks after Fusaka goes live.”
Blobs, introduced via EIP-4844, are temporary data storage units on the blockchain that enable Layer 2 rollups to submit transaction data to Ethereum at a reduced cost. Unlike permanent call data, blobs are automatically deleted after approximately two weeks, which helps minimize storage needs while ensuring data validity.
This mechanism is intended to reduce costs for rollups and enhance Ethereum’s ability to handle more transactions.
To mitigate potential risks, Ethereum’s team has opted for a gradual deployment strategy using Blob Parameter Only (BPO) forks. This means that instead of a single large increase in blob capacity, the thresholds will be raised incrementally.
Consequently, the initial BPO fork, targeted for December 17th, will adjust blob targets from 6/9 to 10/15. A subsequent fork on January 7th, 2026, will further raise these limits to 14/21.
In related news, the announcement of Fusaka’s imminent launch coincides with the Ethereum Foundation’s recent launch of a $2 million security bounty program. This program, running on the Sherlock testnet from September 15th to October 13th, aims to reward researchers for identifying any vulnerabilities within the upgrade.
To encourage early participation, bug reports submitted during the first week will earn double points, while submissions in the second week will receive a 1.5x multiplier.