Ethereum Retires Holešky Testnet Ahead Fusaka Upgrade

Ethereum to Retire Holešky Testnet Ahead of Fusaka Upgrade, Transitioning to Hoodi

Ethereum Prepares to Retire Holešky, Its Largest Testnet

Ethereum (ETH) is preparing to retire Holešky, its largest and most widely used testnet, just two years after its launch. Developers confirmed that the network will be winding down in the coming weeks, marking the end of a critical chapter in Ethereum’s testnet history.

Since its inception, Holešky has played a key role in stress-testing Ethereum upgrades before they hit the mainnet, allowing validators and developers to identify and resolve issues in a safe environment. Its retirement, however, is part of a planned transition, reflecting Ethereum’s evolving testing infrastructure.

From Holešky to Hoodi: A Planned Transition

Holešky’s shutdown is not a sudden move, but a carefully coordinated plan by Ethereum developers. The network is scheduled to close roughly two weeks after the Fusaka upgrade is completed in late September 2025. Fusaka itself is set to go live on Ethereum’s mainnet in November 2025, meaning Holešky will retire well in advance of the mainnet upgrade.

The Ethereum Foundation explained the reasoning behind the shutdown:

“The network served its purpose, enabling thousands of validators to test protocol upgrades, including the Dencun network upgrade and most recently, Pectra…”

Once Holešky is retired, developers will transition to the new Hoodi testnet, which was launched in March 2025 to address technical limitations previously encountered on Holešky.

Why Hoodi Steps In

Hoodi was designed to mitigate technical issues that affected Holešky earlier this year. Specifically, Holešky faced inactivity leaks that led to a large validator exit queue, complicating the testing environment.

With Hoodi, Ethereum aims to provide a more stable and scalable platform for testing protocol upgrades. The testnet already supports the Pectra upgrade and will handle future updates, ensuring continuity for validators and staking operators migrating from Holešky.

For developers building decentralized applications (dApps):

Sepolia will remain the primary testnet for app development.
Ephemery offers short-term validator testing, ideal for quick experiments.

This multi-testnet ecosystem ensures that Ethereum’s development and testing pipelines remain uninterrupted, even as older infrastructure is retired.

The Fusaka Upgrade: Ethereum’s Next Milestone

The retirement of Holešky comes as Ethereum prepares for its next major upgrade, Fusaka, scheduled for early November 2025. Fusaka, short for Fulu-Osaka, aims to make data access for rollups more efficient by distributing workloads across validators.

Key benefits of Fusaka include:

Lighter nodes: Making it easier and cheaper to run Ethereum nodes.
Improved decentralization: By enabling more validators to participate efficiently.
Faster and cheaper Layer-2 transactions: Boosting Ethereum’s scalability for rollups and other off-chain solutions.

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By retiring Holešky ahead of Fusaka, Ethereum ensures that testing environments are fully optimized and free from legacy issues, supporting a smoother mainnet upgrade.

Looking Beyond Fusaka: The Glamsterdam Upgrade

Ethereum’s roadmap continues beyond Fusaka, with the Glamsterdam upgrade penciled in for 2026. Under EIP-7782, Glamsterdam could:

Reduce block times to six seconds, accelerating transaction finality.
Enhance support for zero-knowledge proofs (ZKPs), improving privacy and scalability.
Optimize validation mechanisms, supporting a more robust and decentralized network.

This long-term vision underscores Ethereum’s commitment to continuous innovation, balancing mainnet performance with testnet reliability.

The Legacy of Holešky

Holešky leaves behind a significant legacy in Ethereum’s development history. Key contributions include:

Stress-Testing Major Upgrades: Holešky provided a safe environment for testing Dencun, Pectra, and other protocol upgrades.
Validator Participation: Thousands of validators used Holešky to simulate mainnet conditions, identifying bugs and performance bottlenecks.
Network Stability Insights: Challenges like inactivity leaks informed the design of Hoodi, ensuring more resilient testnets moving forward.

While its operational life is ending, Holešky’s impact on Ethereum’s growth and reliability will persist through the upgraded testnets and mainnet deployments.

Implications for Developers and Validators

For developers and staking operators, the transition from Holešky to Hoodi is a critical adjustment:

Staking infrastructure migration: Validators are moving their nodes and configurations to Hoodi.
Continued upgrade testing: Hoodi will host Pectra and future upgrades, ensuring testing continuity.
dApp development: Sepolia remains the go-to network, allowing developers to continue building without disruption.

Ethereum’s layered testnet approach ensures that no segment of its development ecosystem is left behind, providing both short-term testing options and long-term protocol validation.

Conclusion

Ethereum’s planned retirement of the Holešky testnet marks the end of a key chapter in its development history. Holešky has been instrumental in testing major protocol upgrades, engaging thousands of validators, and providing critical insights for network stability.

The transition to Hoodi, alongside ongoing use of Sepolia and Ephemery, ensures that Ethereum’s testing infrastructure evolves alongside mainnet development, maintaining reliability and scalability.

With the Fusaka upgrade on the horizon, followed by the 2026 Glamsterdam upgrade, Ethereum continues to innovate aggressively, balancing decentralization, scalability, and developer experience.

Holešky may be retiring, but its legacy lives on in the robust Ethereum networks of the future, reinforcing the platform’s status as a leading smart-contract blockchain.