Arbitrum activated ArbOS 61, known as Elara, on Arbitrum One and Arbitrum Nova on Aug. 20 at 17:00 UTC after approval through the ArbitrumDAO's constitutional governance process. The upgrade adds optional protocol-level transaction screening, customizable priority fees and an alternative data-availability interface for dedicated Orbit chains, while introducing new base-fee administration on Arbitrum One and raising the Stylus contract code-size limit from 24 KB to 96 KB. The compliance filters are disabled by default on Arbitrum One and Nova and are intended for operators of application-specific Orbit Layer 3 chains that face regulatory obligations. Owners can configure external compliance providers such as TRM Labs, with support designed for others including Chainalysis and Elliptic, define rules for transfers and contract calls, and enforce restrictions through sequencer checks and delayed-inbox safeguards. Elara also fixes gas-refund logic errors identified during earlier testing, and node operators were required to run Nitro 3.11.3 or later. Further impact will depend on how dedicated-chain operators adopt the new tools and whether ArbitrumDAO separately approves priority-fee functionality on Arbitrum One.