# [Constitutional] AIP: Activate ArbOS 51 (Dia) and Gas Pricing Updates **Type:** Constitutional AIP ## **Abstract** This AIP proposes the activation of ArbOS 51: Dia on Arbitrum One and Arbitrum Nova as well as increases to the gas target and min L2 base fee, along with changes to the L2 pricing algorithm. This on-chain vote proposes to bundle together the following two temperature check votes: 1. [AIP: ArbOS 51 Version 51 Dia](https://snapshot.box/#/s:arbitrumfoundation.eth/proposal/0x33754da4006d0ef38666ec5d5e85fd0966a891a594ab9dc21f23beedea2d330b): which contains relevant Fusaka EIPs, the addition of a MaxTxGasLimit allowing full block utilization, changes to instrument Nitro’s State Transition Function (STF) to price gas based on specific resource usage, native token mint/burn capabilities, and a few bug fixes. 2. [AIP: Raise the gas target, implement improvements to the pricing algorithm, and raise the L2 min base fee](https://snapshot.box/#/s:arbitrumfoundation.eth/proposal/0x4a96a91d162975de0d402b83ca8b8a24e808ca357150120fc0d44ae0bf1cc4a5) The combination of ArbOS 51 and the gas-target/pricing updates will ship as a single integrated release, designated ArbOS 51, which supersedes the originally planned standalone activation of ArbOS 50. Since the ArbitrumDAO has already signaled support for the adoption of the above two AIPs in their respective temperature check votes, this on-chain vote will bundle both of these AIPs for activation on Arbitrum One and Arbitrum Nova with the ArbOS 51 release. Please visit the forum posts for each of the AIPs to learn more. The ArbOS 51 release builds upon ArbOS 40 Callisto and will be shipped as a new mandatory Nitro release and new versions of the rollup contracts for Arbitrum One and Arbitrum Nova, should the ArbitrumDAO vote to pass this proposal. This proposal increments the ArbOS version number to 5x instead of 4x due to technical details that allow for better Orbit chain customizability, as explained[ here](https://docs.arbitrum.io/launch-orbit-chain/how-tos/arbos-upgrade#step-3-schedule-the-arbos-version-upgrade). This proposal only concerns the Arbitrum One and Arbitrum Nova chains, as these two chains are governed by the ArbitrumDAO. On a high level, an ArbOS upgrade can be interpreted as Arbitrum’s equivalent of a hard fork - more can be read about the subject[ here](https://forum.arbitrum.foundation/t/arbitrum-arbos-upgrades/19695). ## **Changes Included** ### **1.** [ **Activation of ArbOS 51 Dia**](https://forum.arbitrum.foundation/t/constitutional-aip-arbos-version-50-dia/29835) ArbOS 51 Dia enables full Fusaka compatibility while introducing native Arbitrum improvements. Visit the original[ Forum Post](https://forum.arbitrum.foundation/t/constitutional-aip-arbos-version-50-dia/29835) to read more details about the proposed changes. Key components include of this ArbOS 51 release include: * [EIP-7951](https://eips.ethereum.org/EIPS/eip-7951): Precompile for secp256r1 Curve Support * [EIP-7825](https://eips.ethereum.org/EIPS/eip-7825): Transaction Gas Limit Cap * [EIP-7642](https://eips.ethereum.org/EIPS/eip-7642): eth/69 - history expiry and simpler receipts * [EIP-7939](https://eips.ethereum.org/EIPS/eip-7939): Count leading zeros (CLZ) opcode * [EIP-7823](https://eips.ethereum.org/EIPS/eip-7823): Set upper bounds for MODEXP * [EIP-7883](https://eips.ethereum.org/EIPS/eip-7883): ModExp Gas Cost Increase * [EIP-7910](https://eips.ethereum.org/EIPS/eip-7910): eth\_config JSON-RPC Method * Enable[ EIP-2537](https://eips.ethereum.org/EIPS/eip-2537): Precompile for BLS12-381 curve operations * Introduce an “Effective Block Gas Limit” in the STF, with a MaxTxGasLimit of 32M gas. The total Effective Block Gas Limit becomes 64M gas (MaxTxGasLimit + MaxBlockGasLimit). This doesn’t change the GasTarget or overall gas per second, only how gas is distributed across blocks. * Instrumentation of the State Transition Function (STF) to track transaction gas consumption across multiple resource types, rather than a single total based on opcodes, including: computation, storage growth, storage access, history growth, and calldata. This work lays the foundation for dynamic, resource-based pricing where fees can adjust based on the most constrained resource on the network and represent one part of Arbitrum’s scaling strategy for lower, more stable fees as demand grows.This[ explainer blog](https://blog.arbitrum.io/dynamic-pricing-explainer/) and[ Vitalik’s post on Multidimensional gas pricing](https://vitalik.eth.limo/general/2024/05/09/multidim.html) are great resources to learn more about this approach to improving how the EVM prices network resource usage. * Native token mint/burn to allow an Arbitrum chain to delegate minting and burning of its native gas token to a trusted bridge provider. Native Token Mint/Burn is proposed to be included in ArbOS 51 Dia for the benefit of Arbitrum Orbit chains (reducing the need for forks) and to streamline development and testing into a single codebase. There are no plans to enable this feature on Arbitrum One or Arbitrum Nova,\*\*\*\* consequently this feature will be explicitly left disabled for Arbitrum One and Arbitrum Nova. To read more about this feature, go[ here](https://arbitrum.notion.site/Enable-Native-Mint-Burn-for-your-chain-s-gas-token-22601a3f59f880be9b99d3d55f982a17). * A number of bug fixes, including: * Standardization of how compressed batch calldata gas units are calculated * A fix to address a divergence in EIP-7702 precompile delegation behavior * An update to address a Stylus-related bug that caused a divergence on Arbitrum Sepolia. More details on this incident can be found[ here](https://forum.arbitrum.foundation/t/security-council-emergency-action-10-13-2025/30093). The below list of Fusaka-related EIPs are not proposed to be included or supported in ArbOS 51 Dia. Visit the original[ Forum Post](https://forum.arbitrum.foundation/t/constitutional-aip-arbos-version-50-dia/29835) to read more details about these EIPs and our decision not to propose them for inclusion in ArbOS 51: * [EIP-7594](https://eips.ethereum.org/EIPS/eip-7594),[ EIP-7918](https://eips.ethereum.org/EIPS/eip-7918), and[ EIP-7892](https://eips.ethereum.org/EIPS/eip-7892): Arbitrum chains do not have blob data markets, nor do they support posting blob data to a non-Arbitrum parent chain * [EIP-7917](https://eips.ethereum.org/EIPS/eip-7917): Arbitrum chains do not have a beacon chain, and therefore, do not have a peer-to-peer layer like Ethereum does * [EIP-7934](https://eips.ethereum.org/EIPS/eip-7934): Arbitrum does not propagate blocks between nodes * [EIP-7935](https://eips.ethereum.org/EIPS/eip-7935): Arbitrum blocks are built differently from those on Ethereum, with different assumptions and mechanics. Therefore, an increase in Ethereum block’s size limit does not need to be replicated or matched with an increase in Arbitrum block size limit. ### **2.** [ **Raising the gas target, increasing the min L2 base fee, & improving the pricing algorithm**](https://forum.arbitrum.foundation/t/aip-raise-the-gas-target-implement-improvements-to-the-pricing-algorithm/30182) As part of our strategy for scaling Arbitrum technology, this proposal includes the AIP to improve the pricing algorithm for Arbitrum One and Nova to reduce the severity, frequency, and duration of high L2 gas prices during periods of elevated demand on the network. Concretely, the proposed changes are to: * Replace the current single gas target and single adjustment window, with a new model that employs multiple (higher) gas targets, measured over multiple adjustment windows, * Raise the long term effective gas target, up from today’s single gas target of 7 Mgas/s (up to a maximum of 100 Mgas/s), * Grant Offchain Labs, in its role as an Arbitrum Aligned Entity, the permission to make additional changes gradually to scale the chain sustainably, and * Increase the minimum L2 base fee from 0.01 gwei per gas to 0.02 gwei per gas. The rationale for this change, alongside details on the specifications and supporting data, can be found[ here in the original AIP](https://forum.arbitrum.foundation/t/aip-raise-the-gas-target-implement-improvements-to-the-pricing-algorithm/30182). ## **Implementation Details** All of the above changes are implemented in a release of Arbitrum Nitro and will be shipped via two separate upgrades: a Nitro node version upgrade and an update with the on-chain rollup contracts on Arbitrum One and Arbitrum Nova. Should this proposal pass, the payload will be executed on-chain and will include the relevant on-chain contract changes, updating the WASM module root, and scheduling of the ArbOS upgrade. The proposed payload changes assume that the Nitro node software for all node operators and validators for Arbitrum One and Arbitrum Nova are updated to a version that supports ArbOS 51. **Audit reports** An independent, third-party audit by Trail of Bits has been completed and the results from the audit can be found below: * [https://docs.arbitrum.io/audit-reports](https://docs.arbitrum.io/audit-reports) **Proposal payload activation details and dates** Note that should this vote pass, the proposal payload[ here](https://github.com/ArbitrumFoundation/governance/pull/366) will trigger the activation of ArbOS 51 at epoch timestamp 17:00:00 UTC on Thursday, January 8, 2026, which is the last step in the implementation process for Constitutional AIPs, as outlined[ here](https://docs.arbitrum.foundation/concepts/lifecycle-anatomy-aip-proposal). This specific date was chosen so that large, complex upgrades (like ArbOS upgrades) can be done so when members from the Arbitrum Foundation, Offchain Labs, and ArbitrumDAO Security Council, are available to assist if necessary. **Verifying the ArbOS 51 code difference** [Click here](https://arbitrum.notion.site/Verifying-the-ArbOS-50-Code-Difference-2a501a3f59f8804cb0a0f9a460020a9d) ## **Implementation Steps** 1. **\[Completed] Forum Proposals and Snapshot Votes**: The included proposals for this vote were initially posted on the ArbitrumDAO forums[ here](https://forum.arbitrum.foundation/t/constitutional-aip-arbos-version-50-dia/29835) and[ here](https://forum.arbitrum.foundation/t/aip-raise-the-gas-target-implement-improvements-to-the-pricing-algorithm/30182). Following discussions with the broader ArbitrumDAO, these proposals were put up for a temperature check vote, where they passed,[ here](https://snapshot.box/#/s:arbitrumfoundation.eth/proposal/0x33754da4006d0ef38666ec5d5e85fd0966a891a594ab9dc21f23beedea2d330b) and[ here](https://snapshot.box/#/s:arbitrumfoundation.eth/proposal/0x4a96a91d162975de0d402b83ca8b8a24e808ca357150120fc0d44ae0bf1cc4a5), respectively. 2. **\[Completed] Engineering Work**: Features were implemented and tested in the Nitro codebase. The engineering work also included smart contract code changes to the Rollup contracts to support ArbOS 51 (nitro-contracts 3.1.0 & nitro-contracts 3.1.1) 3. **\[Completed] Security Audit**: Trail of Bits completed a successful audit; results were published, and can be found here:[ https://docs.arbitrum.io/audit-reports](https://docs.arbitrum.io/audit-reports). 4. **\[Completed] Release Candidate**: Nitro v3.9.3 was released and is now available on Dockerhub as offchainlabs/nitro-node:v3.9.3-8bc5554. The release notes can be found here and this version includes support for ArbOS 51. This is not the final release for mainnet but is instead the first release that adds support for ArbOS 51. The release notes can be found here:[ https://github.com/OffchainLabs/nitro/releases/tag/v3.9.3](https://github.com/OffchainLabs/nitro/releases/tag/v3.9.3). Should this vote pass, the formal and recommended Nitro node version will be communicated to the community. 5. **\[Completed] Arbitrum Sepolia Testnet Deployment**: The originally planned ArbOS 50 Dia has been activated on Arbitrum Sepolia on Thursday November 20 2025. 6. **\[Completed] Arbitrum Sepolia Testnet Deployment**: ArbOS 51 has been activated on Arbitrum Sepolia on Monday December 1, 2025\*\*.\*\* 7. **\[This post] On-chain Vote**: A formal on-chain vote on Tally will be proposed and voted on by the ArbitrumDAO to determine whether ArbOS 51 can be activated on Arbitrum One and Nova 8. **\[Next] Upgrade Execution**: If the above on-chain vote is passed, the ArbOS 51 upgrade will be enacted following[ ArbitrumDAO governance procedures and activation timelines](https://docs.arbitrum.foundation/concepts/lifecycle-anatomy-aip-proposal). The proposal payload in this AIP targets an on-chain activation date of 17:00:00 UTC on Thursday, January 8, 2026 should the vote pass successfully.

[CONSTITUTIONAL] AIP: ArbOS Version 50 Dia

[CONSTITUTIONAL] AIP: ArbOS Version 50 Dia

[CONSTITUTIONAL] AIP: ArbOS Version 50 Dia

[CONSTITUTIONAL] AIP: ArbOS Version 50 Dia