Fusaka Devnet-3 Faces Non-Finality Challenges, Devnet-5 on Horizon

Ethereum’s upcoming Fusaka upgrade is undergoing rigorous testing, but recent developments on Devnet-3 revealed unexpected non-finality issues. While some clients performed stably, others faced significant delays & syncing bottlenecks.

Developers are now preparing fixes and planning the next phase, Devnet-5, which will act as a stability checkpoint before Fusaka progresses toward mainnet activation.

• Devnet-3 Non-Finality Issues
• Client Performance & Bottlenecks
• Roadmap Toward Devnet-5

Devnet-3 Non-Finality Issues

Ethereum’s Devnet-3, expected to run in non-finality for only two days, extended nearly a full week due to unexpected challenges. The prolonged instability highlighted weaknesses in validator exit processing and syncing reliability across different clients.

Developers emphasized that such extended periods of non-finality were crucial for stress-testing, even if they revealed serious inefficiencies.

Client Performance & Bottlenecks

Performance varied widely across clients:

1. Prysm nodes remained largely stable throughout testing.
2. Lighthouse, Lodestar, and Nimbus encountered memory leaks & syncing delays, reducing participation levels to only 50–55%.
3. Efforts to restore finality included targeted validator exits, but these processed slower than expected, exposing bottlenecks that need immediate resolution before advancing to broader testnet deployments.

Roadmap Toward Devnet-5

To address these challenges, core developers plan to introduce client-side fixes (from Lighthouse, Teku, & Lodestar) before rerunning another non-finality test. If results show strong recovery, Ethereum will launch Devnet-5 as a “fix-only” validation stage.

Devnet-5 will serve as a checkpoint to confirm ecosystem stability, ensuring Fusaka rolls out on a tested, secure foundation before scheduling public testnet forks.

The difficulties on Devnet-3 underline the importance of Ethereum’s careful upgrade path. By diagnosing client weaknesses and reinforcing validator exit efficiency, developers are laying the groundwork for a more resilient network. With Devnet-5 on the horizon, the community moves closer to a stable & secure Fusaka release.

If you find any issues in this blog or notice any missing information, please feel free to reach out at yash@etherworld.co for clarifications or updates.

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