Arbitrum has activated its ArbOS 61 Elara upgrade, adding optional compliance filtering and priority-fee support for dedicated blockchains while introducing changes to fee management and smart contract capacity on Arbitrum One.
According to Arbitrum’s official announcement, it was approved through Arbitrum governance and activated on Arbitrum One and Arbitrum Nova on August 20 at 17:00 UTC. The upgrade gives businesses and developers greater flexibility to build application-specific blockchains with customized compliance and transaction-ordering features.
The compliance features do not automatically apply to Arbitrum One. They are configurable capabilities designed for dedicated-chain environments.
Compliance filters added
One of the main additions is protocol-level compliance filtering for dedicated blockchains. Chain owners can create rules that prevent certain transactions from being processed based on restricted addresses or other defined conditions.
The Arbitrum Platform allows businesses to select their compliance provider and configure restricted-address or access policies. Arbitrum says the system is initially compatible with providers including TRM Labs and is designed to support others such as Chainalysis and Elliptic.
The filtering operates at two levels:
- Sequencer: Can reject transactions that violate configured rules before they enter a block.
- Onchain guardian: Can prevent restricted transactions from bypassing the sequencer through Arbitrum’s force-inclusion mechanism.
Transactions submitted through the parent chain’s Delayed Inbox can be checked by an onchain guardian, causing restricted transactions to fail during state execution. Arbitrum said the feature gives businesses a clearer path to launching regulated onchain products while maintaining control over dedicated networks.
Priority fees remain optional
Elara also introduces support for priority fees on dedicated chains. These fees allow users to add tips that can potentially influence the order in which transactions are processed.
The capability is disabled by default and must be activated by the chain owner. Operators would also need suitable sequencer logic if they want priority fees to directly affect transaction ordering.
The change could eventually support more advanced transaction-ordering systems. On Arbitrum One, however, priority-fee collection and Priority Gas Auction transaction ordering would require a separate ArbitrumDAO vote. In other words, Elara provides the technical foundation, but does not activate the feature on Arbitrum One.
New base fee controls
Arbitrum One also receives a new BaseFeeManager contract designed to make minimum base-fee adjustments more responsive to changing network conditions.
The contract allows Offchain Labs to adjust the minimum L2 base fee within a governance-approved range of 0.01 to 0.10 gwei. The delegation is limited and expires two years after mainnet activation.
Any adjustment must be publicly announced through the Arbitrum forum, while ArbitrumDAO can remove the delegation through its standard governance process. In addition, the upgrade does not automatically increase Arbitrum One fees. It instead creates a mechanism for making limited adjustments when network conditions require them.
Larger Stylus contracts
Elara also increases the code-size limit for Stylus smart contracts from 24 KB to 96 KB. The change is aimed at developers building larger Rust-based applications on Arbitrum’s Stylus environment. A higher limit can reduce the need to split larger applications across multiple contracts and make it easier to use bigger Rust libraries.
The increase applies only to Stylus contracts. It does not change Solidity’s contract-size limit or existing EVM rules.
More tools for dedicated chains
Another addition is an Alternative Data Availability API. It allows dedicated-chain operators to connect external data-availability providers without maintaining custom Nitro forks.
This could reduce infrastructure maintenance for teams operating application-specific chains and allow them to focus more resources on their products. Arbitrum One is not expected to use the API because its transaction data settles on Ethereum.
With Elara now live, Arbitrum is expanding the tools available to organizations building customized blockchains. The next major developments will depend on how dedicated-chain operators adopt the new features and whether ArbitrumDAO approves separate proposals for priority-fee functionality on Arbitrum One.
