Arbitrum activates ArbOS 61 Elara upgrade

Arbitrum has activated the ArbOS 61 ‘Elara’ upgrade, introducing several infrastructure enhancements across its network. A primary feature of the update is the introduction of optional protocol-level transaction screening tools. These compliance filters are designed specifically for operators of dedicated Orbit chains—Arbitrum’s customizable Layer 3 networks—to help them meet specific regulatory obligations.

Crucially, these compliance tools are disabled by default on Arbitrum One and Arbitrum Nova. For Orbit chain owners, the filtering is configurable; they can select external providers like TRM Labs or Chainalysis to manage restricted-address lists. Enforcement occurs at the sequencer level and through an onchain guardian to prevent users from bypassing rules via the force-inclusion path.

The upgrade also provides a significant capacity boost to Stylus, the framework allowing developers to use languages such as Rust and C++. The compressed contract code size limit on Arbitrum One has increased fourfold, from 24 KB to 96 KB. Additionally, Elara introduces customizable priority fees for Orbit chain operators, an alternative data-availability interface, and fixes previous gas-refund logic errors.