Ethereum’s Major Update Date Has Changed, Brought Forward – Here’s the New Date

Ethereum (ETH) developers have set the mainnet activation date for the long-awaited Fusaka update as December 3, 2025. The update schedule, previously projected to be extended to 2026, has thus been brought forward.

The decision was made following tests on Fusaka Devnet-5. According to a summary by Ethereum researcher Christine Kim, the tests revealed some software bugs and installation problems, leaving developers with less time to measure data capacity.

After the testnet was stable for a short time, developers agreed to increase the blob capacity in two phases: first to 10/15 blobs per block, then to 14/21 blobs. In Ethereum, a blob refers to temporary data packets used by rollups, or scaling solutions, to send transaction data to the chain at a lower cost.

Devnet-6, which will be launched soon, will be used to verify these capacity increases. The numbers are then planned to be migrated to public test networks and the mainnet.

In the process, developers discovered that Prysm, one of Ethereum's major validator clients, was struggling under high load and was generating “orphan blocks.” Orphan blocks are blocks that were correctly generated by a validator but were rejected because the network chose a different block at the same point.

Ethereum researcher Justin Traglia noted that a bug in the ckzg library used to verify blobs has been fixed. He also added that a lighter version is being prepared to make upgrades easier for client teams.

*This is not investment advice.