Ethereum Glamsterdam Upgrade Goes Live on Sepolia Testnet Ahead of Mainnet
Ethereum’s next major upgrade, Glamsterdam, activated on the Sepolia test network on Oct. 6, moving one of the year’s most consequential blockchain changes into its final public testing phase, according to reports from crypto outlets including CoinCodeCap and TradingView.
Sepolia is a public rehearsal network where developers, node operators and application builders test new Ethereum rules under realistic conditions without risking real money. The Glamsterdam fork went live at 13:53 UTC, roughly 9:53 a.m. Eastern, and operators had been told to update their software ahead of time.
The headline feature is enshrined proposer-builder separation, a change that writes the division of labor between block builders and validators directly into Ethereum’s protocol. Today, most Ethereum blocks are assembled with the help of outside software called relays, and the upgrade aims to make that handoff more transparent and less dependent on third parties.
Glamsterdam also introduces block-level access lists, which record the accounts and storage touched in each block. The feature is designed to help the network process transactions more efficiently, including work done in parallel, and to set prices for network resources more accurately.
Another goal is higher capacity. Developers are testing a gas limit of 200 million on Sepolia, roughly triple the current level, to see how much activity the network can handle. The figure is a test parameter rather than a promise for the live network, and the final mainnet number has not been set.
For ordinary ETH holders, the Sepolia activation changes nothing directly. The Ethereum Foundation has said holders do not need to take any action, and no funds move or unlock as part of a testnet fork.
What matters is what comes next. Developers will watch Sepolia for problems before scheduling the upgrade on the Hoodi testnet and eventually on the main network, which handles real transactions. Community trackers expect the mainnet activation sometime in the fourth quarter of 2026, though no date has been confirmed.
If Glamsterdam succeeds, Ethereum would take a meaningful step toward its long-running goal of handling far more activity without raising costs for users. If the testnet reveals bugs, the timetable slips. Either way, Oct. 6 marked the moment the upgrade stopped being a plan and started being a live experiment.