Ethereum's Glamsterdam Testnet Launches with Key Scaling Upgrades
Major protocol changes aim to enhance L1 throughput and validator efficiency
1Core Scaling Upgrades
Glamsterdam combines Amsterdam execution layer and Gloas consensus layer upgrades, introducing enshrined proposer-builder separation (ePBS) and block-level access lists (BALs). These changes fundamentally alter block production and validation processes to increase L1 throughput. ePBS moves builder-proposer coordination into the protocol itself, reducing reliance on middleware. BALs record account access patterns to enable parallel transaction validation and more efficient state root computation.
2Proposer-Builder Separation
EIP-7732 formalizes the division between block proposers and builders within Ethereum's consensus protocol. Proposers now include builder commitments to execution payloads, with builders revealing payloads later. The protocol automatically handles payments between parties, eliminating trust requirements in this exchange. This change also decouples consensus validation from execution validation, giving validators extended time to verify payloads. A new timeliness committee monitors whether builders reveal payloads and data blobs on schedule.
3Block-Level Access Lists
EIP-7928 introduces enforced access lists that document all account and storage interactions during block processing, along with post-transaction state changes. These lists enable clients to parallelize state reads from disk and transaction validation while optimizing state root calculations. Combined with ePBS, BALs create infrastructure for scaling execution capacity without overwhelming node operators with impractical validation demands. Both features represent foundational improvements for Ethereum's long-term scalability roadmap.
4Gas Model Updates
Glamsterdam overhauls gas pricing to better reflect actual resource consumption. EIP-8037 separately meters state creation costs while EIP-8038 updates state access pricing. Additional adjustments affect intrinsic transaction gas, calldata, access lists, and block gas accounting. Developers must test contracts against these new rules, particularly those relying on fixed gas stipends or hardcoded limits. The upgrade includes a repricing impact guide to help identify affected contracts needing adjustments.
5Developer Enhancements
The upgrade introduces ETH transfer logs, a slot-number opcode, increased maximum contract size, deterministic factory contracts, and new stack manipulation instructions. Consensus changes add forward-compatible data structures while excluding slashed validators from proposal rights. The upgrade also modifies validator exit and consolidation processes. These collective improvements aim to streamline developer experience while maintaining network security during the transition.
6Activation Timeline
Sepolia testnet activation occurs at epoch 353,024 (October 6, 2026, 13:53:36 UTC), with client updates required beforehand. Hoodi and mainnet dates remain undetermined. Prysm 7.2.0 supports Sepolia but defaults to a 60M gas limit post-activation - validators needing 200M must configure this explicitly. Execution layer clients including Besu 26.9.0 and go-ethereum 1.17.6 require updates for compatibility. Builder and validator tooling guidance will follow once confirmed.
7Security Preparations
The Ethereum Bug Bounty Program expanded coverage to include Glamsterdam specifications and EIPs. Client implementations qualify for bounties once their releases appear in official tables. The program offers reward multipliers for critical vulnerabilities during this transition period. Validators and builders must review new duties and interfaces, particularly around ePBS operations. Node operators running external block-building infrastructure need specific upgrade instructions for compatibility.
8Implementation Requirements
All Sepolia node operators must update both execution and consensus layer clients before the October activation. Validators need updated beacon nodes and validator clients, with special attention to ePBS-related configuration changes. Application developers should test contracts against new gas accounting rules and verify compatibility with updated opcodes and interfaces. Mainnet participants can await separate announcements, as this upgrade currently only affects Sepolia testnet.