The Snapshot vote has already been posted and has passed successfully at the time of writing. Not adopting EIP-7623 initially will change how Arbitrum chains calculate gas costs for calldata-heavy transactions, compared to L1, but will otherwise not alter how gas is estimated and charged to the user at the application layer. Operations and use cases that rely on calldata-heavy transactions will have their gas costs calculated the same way as it is done today, pre-Pectra.
Yes it is possible. Nitro node version 3.5.3 and nitro-contracts 3.0.0 or 2.1.3 should be used for chains settling to a Pectra-enabled Ethereum chain (like Sepolia or Holesky). Should this vote pass, a new Nitro version with ArbOS 40 will be released for Arbitrum one and Arbitrum nova node operators to use as a mandatory upgrade.
Yes - Arbitrum builders across protocols and developer tooling have been consulted in anticipation for this upgrade on Pectra. This includes Orbit chain owners and Rollup-as-a-Service (RaaS) teams who may need to apply a small patch to ensure their chains are compatible with a parent chain that has upgraded to use Pectra.
Yes - Step 6 is the formal deployment of a release candidate of the Nitro node software that supports Pectra, while Step 2 is the temperature check vote held on Snapshot.
It is our understanding that client teams have already released their Pectra-supported versions for Ethereum Holesky, including Geth’s 1.15.0 release. We strongly recommend following Ethereum Core Development discussions on https://ethereum-magicians.org/ and in their respective All Core Devs call, rather than this forum post.
This is meant to be an informative message.
These changes refer to modifications that Orbit chains may want to make to ArbOS and to prevent versioning collisions between their modifications and official ArbOS releases. For example, if an Orbit chain wanted to modify ArbOS 40 and release their modifications as ArbOS 41, then the official Offchain Labs ArbOS release versions would not conflict since the next official version would be ArbOS 50.
With any upgrade to the Arbitrum tech stack (including ArbOS 20 for Ethereum’s Dencun upgrade in March 2024), Orbit chains have full discretion over what ArbOS version to use for their chain and what customizations they want to make. We generally recommend Orbit chains upgrade to a new ArbOS release approximately 30 days after the release has been in production on Arbitrum One or Arbitrum Nova (pending governance).
As defined in the ArbitrumDAO’s Constitution, a temperature check vote is optional and is considered a matter of good governance practice. Furthermore, in the Steps to Implement section, there are clear steps that follow after the temperature check that a security audit by Trail of Bits is underway, and that a public report will be ready by the time this proposal is submitted to Tally for a formal on-chain vote. The vote here is to signal the readiness of the DAO to have this upgrade ready on both private devnets and Arbitrum Sepolia for further testing.
Hello! We’re preparing to propose an upgrade to the Arbitrum Nitro stack to support Ethereum’s upcoming Pectra hard fork, via ArbOS 40 Callisto and wanted to give our ecosystem partners and the ArbitrumDAO a status update. Please refer to the original AIP forum post above, for details.
At the time of writing, the proposal to bring Pectra’s changes to Arbitrum via ArbOS 40 has already passed a temperature check vote on Snapshot and a security audit has recently wrapped up.
Below are a few critical dates, around what will happen next, that we wanted to communicate with the ecosystem:
May 5, 2025: ArbOS 40 Callisto will activate on Arbitrum Sepolia
Arbitrum Sepolia node operators must upgrade to the soon-to-be released Nitro v3.6.x ahead of this date to continue syncing the chain. A follow-up message will be circulated via social channels and Arbitrum documentation when this release is ready.
May 12, 2025: ArbOS 40 Callisto Tally Proposal for Arbitrum One and Arbitrum Nova
The formal constitutional on-chain proposal to activate ArbOS 40 on Arbitrum One and Arbitrum Nova is scheduled to be posted on May 12, to commence on May 15.
Mid-June, 2025: ArbOS 40 Callisto will be activated on Arbitrum One and Arbitrum Nova, assuming the ArbitrumDAO passes the proposal.
Node operators (for Arbitrum One and Arbitrum Nova) will be asked to upgrade their Nitro nodes to the soon-to-be-released version that supports ArbOS 40. A follow-up message will be circulated via social channels and Arbitrum documentation when this release is ready.
Mid-July, 2025: ArbOS 40 Callisto will be formally supported for Arbitrum Orbit chain owners and operators.
Action will be required for Node Operators to upgrade both their chains’ Arbitrum Nitro nodes and rollup contracts. Further documentation, instructions, and release notes for how to do this will be shared.
Further documentation, upgrade instructions, and release notes for Nitro v3.6.x will be shared shortly. Node operators should ensure that their infrastructure is prepared for the Arbitrum Sepolia upgrade.
We originally supported this constitutional proposal to activate ArbOS 40 during the temp check. Also, with the positive conclusion of the security audit, we were confident in supporting the proposal during the onchain vote.
LobbyFi’s rationale on the price and making the voting power available for sale for this proposal:
Following the rationale posted previously, he auction be made available.
The instant buy will be priced at 1% (instead of 0.1%) of our voting power’s worth in ETH terms. This is calculated as 18,422,193 ARB * 1%, which equals approximately 29.25 ETH.
I’m voting yes cause this update helps Arbitrum stay up to date with Ethereum changes, like making wallets more smart. Also it fix small bug and makes things work smoother for devs and users.
I wanted to clarify whether there were any calculations on future profits from commissions?
The thing is that Blobs have changed, so Arbitrum should, in theory, give less to the main Ethereum network for transferring data from Arbitrum.
Will Arbitrum receive more for commissions because of this? If so, how much?
gm, voted FOR - supporting Pectra and the other updates on Arbitrum.
@Arbitrum would be great if next time you could include a brief summary (on the forum or Tally) outlining how the audit findings - especially high severity ones - have been addressed.
The following reflects the views of the Lampros DAO governance team, composed of Chain_L (@Blueweb), @Euphoria, and Hirangi Pandya (@Nyx), based on our combined research, analysis, and ideation.
We are voting FOR this proposal in the Tally voting.
We are in support of the ArbOS 40 Callisto upgrade as it introduces meaningful improvements with the Pectra upgrade. With the security audit concluding positively, we are confident in supporting the proposal during the on-chain vote. This upgrade will also help Arbitrum stay up to date with changes happening on Ethereum.
Since this AIP ensures Arbitrum stays compatible and aligned with those changes, especially through enhanced Stylus support.
For us, maintaining interoperability with Ethereum and staying in sync with its technical evolution is essential.
We support it as a move that reinforces ecosystem cohesion.
I voted FOR.
This AIP ensures Arbitrum’s stack is up to date with all the enhancements of Pectra, let’s get this in asap.
Optimism got this done within 48 hours of ETH’s Petra update, we are still voting on it, in the future I’d like to see more forward planning from @Arbitrum and @offchainlabs to have the audit, and vote lined up earlier in sync with next ETH protocol upgrades. Speed is a competitive advantage, builders wanting to experiment and prototype with new transformative functionality will pick the tech provider who’s live and ready.
I have voted FOR this proposal because it is key to have improvements from Pectra on Arbitrum Chain and I don’t see any points of not doing it.
In my opinion this kind of proposal could be done in an Optimistic way, @Arbitrum and @offchainlabs could proposed it to the DAO with a security report, if after 2 or 3 days no major Delegate put a veto or asked for a vote, it is automatically implemented. This could be a way to gain in efficiency cf @KlausBrave comment and avoid to have all delegates to vote on a proposal that is making consensus.
I have voted “Yes” to this proposal on Tally. There are significant advantages to staying “in-sync” with Ethereum, and significant disadvantages not to, so it’s a simple decision.
I appreciate @paulofonseca linking the audit reports, and I wish they had been provided more “up-front” rather than relying on a delegate to link them.
