The Ethereum network has completed the Fusaka upgrade with the final BPO-2 fork, a planned change aimed at lowering data costs for Layer 2 rollups and reducing fees for end-users. Core developers confirmed the upgrade and it was reported by The Block on December 11, 2024, marking the last step of a staged rollout that began with BPO-1. The upgrade adjusts how the protocol handles large ‘blob’ data packets used by rollups, expanding available space per block without requiring users to move funds or change wallets.
Overview of the Ethereum Fusaka Upgrade
Fusaka is a targeted optimization of Ethereum’s blob-handling parameters to make rollup data posting cheaper and more predictable. The work was split into two sequential forks: BPO-1 and BPO-2, with BPO-1 activating on December 9, 2024 and BPO-2 following just days later to apply the new capacity parameters. Together these stages aimed to increase blob capacity while preserving network stability through a cautious, staged deployment.
Key elements
- Purpose: reduce data costs for Layer 2 rollups and lower end-user fees.
- Two stages: BPO-1 (initial protocol changes) and BPO-2 (parameter increases).
- Timeline: BPO-1 activated December 9, 2024; BPO-2 completed on December 11, 2024.
Technical Details of the BPO-2 Fork
The BPO-2 fork raises both the target and the maximum number of blobs that can be included in each new block, effectively doubling the target capacity for blob data. By increasing these limits, the protocol creates more space for the large data packets rollups post to Ethereum, which directly addresses prior congestion in blob space. Before the upgrade, analytics showed blob capacity often filled to the limit, contributing to auction-style spikes in data fees; BPO-2 increases supply to ease that pressure.
The change is backward-compatible and does not require action from most everyday users or decentralized application developers. Client teams implemented the staged activation so the parameter increases could be applied after the initial protocol changes were already live, reducing operational risk during rollout.
Impact on Layer 2 Rollups and Users
Layer 2 rollups that post compressed transaction data as blobs—such as Arbitrum, Optimism, and Base—stand to see their per-blob posting costs fall as a result of larger blob capacity. Because rollups bundle many end-user transactions into those posted blobs, lower data costs at the protocol level can translate into lower fees charged to users. In practical terms, this upgrade targets the cost structure of rollups rather than changing how end-users interact with wallets or dApps.
If you follow broader Ethereum developments, this upgrade is the next step after Dencun, which introduced proto-danksharding and blob transactions. Fusaka refines parameters based on real-world usage to make fee behavior more predictable and stable for rollup data.
Expert Insights and Future Implications
The strategic doubling of target blob capacity is expected to create a more stable and predictable fee market for rollup data, reducing the frequency of sudden fee spikes caused by full blob space. This upgrade is an incremental, parameter-level improvement that builds on earlier protocol changes rather than a wholesale redesign. As a result, it continues Ethereum’s pattern of iterative scalability work focused on rollup economics and data availability.
Why this matters
If you operate mining or validation hardware, run a node, or simply use Ethereum apps, the Fusaka changes are unlikely to force any immediate operational changes on your side. The upgrade is backward-compatible and does not require users to move assets or perform migrations. At the same time, if you use Layer 2 services for lower fees, you may start to see reduced transaction costs as rollups benefit from lower data posting prices.
For those tracking network performance or costs, the upgrade reduces a known bottleneck in blob space that previously led to unpredictable fee spikes. That change improves the fee landscape for rollups and their users while keeping the protocol behavior consistent for everyday interactions.
What to do?
As an individual operator with between one and a thousand devices in Russia, you do not need to change wallets or migrate tokens because of Fusaka. The update is applied at the protocol level and is backward-compatible, so your balances and existing transactions remain unaffected. If you run a node, check that your client is up to date with the latest release from your chosen implementation (for example, Geth, Nethermind, or Besu) to ensure continued compatibility.
If you use Layer 2s to save on fees, monitor transaction costs over the coming weeks to see whether rollups pass savings to end-users. For a concise technical follow-up, see analysis on Mining and scaling, and for broader context about upcoming Ethereum changes, consult our overview Ethereum in 2025.
Quick checklist
- Do nothing with wallets or tokens—no migration required.
- If you operate a node, update your client to the latest stable release.
- Watch Layer 2 fees and rollup announcements for passed-through savings.
