Arbitrum activates ArbOS 61 Elara upgrade with optional compliance filters for Orbit chains

Arbitrum activated the ArbOS 61 Elara upgrade on August 20, 2026, introducing optional protocol-level transaction screening and priority fees for dedicated Orbit chains. The upgrade, approved by the ArbitrumDAO after testing on the Sepolia testnet, leaves compliance filters disabled by default on Arbitrum One and Nova. Additionally, Elara expands Stylus contract capacity on Arbitrum One from 24 KB to 96 KB and delegates temporary base-fee adjustment authority to Offchain Labs.

ArbOS 61 Elara upgrade

• ▪Arbitrum activated the ArbOS 61 Elara upgrade on August 20, 2026, at 17:00 UTC across Arbitrum One and Arbitrum Nova.
• ▪The ArbOS 61 Elara upgrade fixes gas-refund logic errors that surfaced during testing phases of the previous ArbOS 51 Dia release.
• ▪The ArbOS 61 Elara upgrade requires all Arbitrum node operators to upgrade their systems to Nitro version 3.11.3 or higher to remain in consensus.

Orbit chain compliance filtering

• ▪Arbitrum Orbit chain owners can configure compliance filtering under ArbOS 61 Elara by selecting external compliance providers like TRM Labs or Chainalysis to produce restricted-address lists.
• ▪The ArbOS 61 Elara upgrade introduces optional, protocol-level transaction screening tools that are disabled by default on Arbitrum One and Arbitrum Nova.
• ▪Compliance filtering in ArbOS 61 Elara operates via sequencer simulation and a sentinel-guardian system to prevent restricted users from using the force-inclusion path.
• ▪Arbitrum technical documentation recommends that Orbit chains wait at least 30 days after the ArbOS 61 Elara release on Arbitrum One before adopting compliance filtering.

Priority fee configuration

• ▪Activating priority-fee collection on Arbitrum One requires a separate constitutional ArbitrumDAO vote, as ArbOS 61 Elara only installs the underlying capability.
• ▪The ArbOS 61 Elara upgrade allows dedicated Orbit chain owners to collect priority fees, but the feature is disabled by default and requires explicit activation.

Base fee manager delegation

• ▪The delegation of base-fee adjustment authority to Offchain Labs under ArbOS 61 Elara is limited to a range of 0.01 to 0.10 gwei, expires after two years, and can be removed by the ArbitrumDAO.
• ▪The ArbOS 61 Elara upgrade introduces a BaseFeeManager contract that delegates authority to Offchain Labs to adjust the minimum Layer 2 base fee on Arbitrum One.

Stylus capacity expansion

• ▪The ArbOS 61 Elara upgrade expands the compressed contract code-size limit for Stylus contracts on Arbitrum One from 24 KB to 96 KB.
• ▪The fourfold expansion of Stylus contract capacity in ArbOS 61 Elara does not apply to Solidity contracts.

ArbitrumDAO governance approval

• ▪The ArbitrumDAO approved the ArbOS 61 Elara upgrade through its constitutional governance process, which involved ARB token holders voting on the changes before they went live.
• ▪The ArbOS 61 Elara governance proposal first hit the Arbitrum Sepolia testnet on June 29, 2026, allowing roughly seven weeks of testing before mainnet deployment.