Ethereum to Close Its Largest Testnet, Holesky, After Fusaka Upgrade

A fresh slate of Ethereum testnets is replacing Holesky , the once-massive staging ground now set for shutdown after two years of service. The wind-down will occur two weeks after the Fusaka upgrade is finalized later this year, at which point client and infrastructure teams will cease providing support. Fusaka is set to make Ethereum rollups cheaper and faster by spreading out the “data storage work” more evenly across validators. Holesky went live in 2023 to stress-test Ethereum’s proof-of-stake machinery at scale. It quickly became the largest public testnet, providing thousands of validators with a platform to trial upgrades before they were deployed on the mainnet. Major milestones, such as the Dencun and Pectra upgrades — which lowered transaction costs and upgraded validator efficiency, among other features — were run through Holesky first. However, cracks began to appear as the network aged. Holesky encountered “inactivity leaks” after Pectra’s activation in early 2025, a term referring to validators going offline in large numbers, which created a significant backlog for those attempting to exit. The result was months-long queues that made it impractical to test the full validator lifecycle. For developers needing fast feedback loops, Holesky had become more of a roadblock than a tool. That’s why Ethereum launched Hoodi in March 2025, a clean-slate testnet built to sidestep Holesky’s problems while carrying forward its role as the go-to environment for validator and staking provider testing. Alongside Hoodi, Sepolia continues to serve as the main testnet for dapps (decentralized apps) and smart contracts, while Ephemery offers quick-reset validator cycles every 28 days. Ether (ETH) was trading at $4,380 in Asian morning hours Tuesday, nearly flat over the past 24 hours.