Arbitrum flipped the switch on its ArbOS 61 “Elara” upgrade on August 20 at 17:00 UTC, rolling out a bundle of infrastructure changes across both Arbitrum One and Arbitrum Nova. The most eyebrow-raising feature: optional protocol-level transaction screening baked directly into the network’s architecture.
Before anyone starts drafting outrage tweets, a key distinction matters here. The compliance-filtering tools are disabled by default on Arbitrum One and Nova. They’re designed exclusively for operators of dedicated Orbit chains, Arbitrum’s customizable Layer 3 networks, who face regulatory obligations in their specific jurisdictions.
What Elara actually changes
Stylus, Arbitrum’s framework that lets developers write smart contracts in languages like Rust and C++ instead of just Solidity, got a significant capacity boost. The compressed contract code size limit jumped from 24 KB to 96 KB on Arbitrum One. That’s a fourfold expansion, meaning developers can deploy substantially more complex applications without running into size constraints that previously forced awkward workarounds like splitting contracts across multiple deployments.
Beyond Stylus, Elara introduces customizable priority fees for Orbit chain operators. The upgrade also ships an alternative data-availability interface for dedicated chains and modifies base-fee administration across the network. On the housekeeping side, Elara fixes gas-refund logic errors that surfaced during earlier testing phases, cleaning up technical debt carried over from the previous ArbOS 51 “Dia” release.
