Ethereum 'Glamsterdam' upgrade expected H1 2026

Ethereum Foundation documents published in 2026 show the network’s next major upgrade, known as Glamsterdam, is still targeted for the first half of 2026, but developers have not set a mainnet fork date. The roadmap page on ethereum.org says Glamsterdam is “planned for H1 2026,” while recent Ethereum Foundation blog posts describe the upgrade as still in active hardening and devnet testing. May 11 updates from the Ethereum Foundation said core developers had spent a week in Svalbard, Norway, preparing Glamsterdam and came away with a stabilized ePBS setup, a multi-client devnet and an end-to-end tested external builders pipeline across nearly all clients. That progress followed an April 10 checkpoint that said the fork date would only be announced after stable devnets, client releases, security reviews and testnets. (ethereum.org) May 15 market data showed ether closing near $2,223 on CoinMarketCap and $2,223.59 on CoinGecko, below the $2,261 figure cited in the report you provided. Intraday pricing varied across providers, with CoinDesk showing about $2,254 early on May 15. ### Where does the H1 2026 timeline actually come from? April 13 roadmap language on ethereum.org says Glamsterdam is an “upcoming Ethereum upgrade planned for H1 2026.” That page describes the fork as the next step after Fusaka and says it is meant to reorganize how Ethereum creates and verifies blocks as the network scales. (blog.ethereum.org) January 20 and April 10 Ethereum Foundation checkpoint posts gave the more operational version of that timeline. (coinmarketcap.com) The January post said the upgrade was fully scoped and moving through devnets, while the April post said developers would not announce a mainnet date until testnets were confirmed stable. ### What is ePBS, and why is it central to Glamsterdam? Ethereum.org says Glamsterdam’s headliner is enshrined Proposer-Builder Separation, or ePBS, which moves part of block building into the protocol rather than relying on off-protocol arrangements. (ethereum.org) The roadmap page says the change is intended to remove reliance on third-party relays and support higher throughput while keeping node operation manageable. April 10 protocol notes said ePBS splits block production into two parties acting in sequence inside consensus, creating new failure and coordination cases around “partial blocks.” The Ethereum Foundation described that work as a major sticking point because it touches both consensus and execution behavior. (blog.ethereum.org) ### What else is bundled into Glamsterdam besides ePBS? February 18 protocol priorities from the Ethereum Foundation listed ePBS, repricings and other scaling components as the main 2026 delivery items for Glamsterdam. (ethereum.org) January and April updates also highlighted Block-level Access Lists, or BALs, plus gas repricing work aimed at lifting capacity without pushing hardware costs too far for node operators. (blog.ethereum.org) May 11 notes from Svalbard said developers had established a “200M gas limit floor” as a credible post-Glamsterdam target derived from ePBS, BAL optimizations and EIP-8037 repricing. The same update said EIP-8037 had been finalized and benchmarked on bal-devnet-6. ### How far along is the testing now? January 20 status notes said BALs already had devnets while ePBS was still behind because it was more complex. (blog.ethereum.org) By April 10, the Ethereum Foundation said developers were aiming for the first generalized Glamsterdam devnet once the ePBS devnet stabilized. May 11 marked the clearest progress update so far. The Ethereum Foundation said a multi-client Glamsterdam devnet was running and that the external builders pipeline had been tested end-to-end across nearly all clients, language that indicates cross-client interoperability work is underway but not finished. (blog.ethereum.org) That last point is an inference from the stated testing status, not a separately announced milestone. (blog.ethereum.org) ### What should readers watch next? The Ethereum Foundation said on April 10 that the next formal sequence is stable feature-complete devnets, client releases, final security reviews and then public testnets. Only after those testnets are confirmed stable will developers announce the mainnet fork date. May 11 protocol notes said the immediate focus is “shipping Glamsterdam,” while ethereum.org’s roadmap page still lists the fork in H1 2026. (blog.ethereum.org) For readers tracking progress, the Ethereum Foundation blog, ethereum.org’s Glamsterdam roadmap page and Forkcast call summaries are the named places developers themselves point to for the next milestone. (blog.ethereum.org)