Arbitrum Nitro v3.10 ships with a May 18 Sepolia deadline. Arbitrum One still doesn't have a date.
Sepolia operators have four days to upgrade or lose sync. The Arbitrum One ArbOS 60 activation date is still open.
CryptoVibe Desk · arbitrum · nitro · arbos
- →Offchain Labs shipped Nitro v3.10.0 on May 11, requiring Arbitrum Sepolia operators to upgrade before ArbOS 60-rc.5 activates on May 18 at 17:00 UTC.
- →Any Sepolia operator who misses the May 18 window will fall out of sync. Arbitrum One's ArbOS 60 date remains unset, making this a testnet staging event for now.
- →Watch for the Arbitrum One ArbOS 60 upgrade date within two weeks of May 18 Sepolia activation.
- ArbOS → Arbitrum's internal software layer that defines how the chain processes transactions and applies protocol upgrades.
- Sepolia → Ethereum's main test network, where protocol upgrades run first before being applied to the real chain.
- WAVM module root → A unique hash that identifies which version of Arbitrum's fraud-proof verification program is active on the chain.
ArbOS 60-rc.5 activates on Arbitrum Sepolia on May 18 at 17:00 UTC. Offchain Labs shipped Nitro v3.10.0 on May 11 to carry it, per the release. Any Sepolia operator still on an older build at activation will fall out of sync.
The Arbitrum One mainnet date hasn't been set. That makes v3.10 a staging release for now, not a mainnet upgrade story. The logic: run ArbOS 60-rc.5 through live testnet conditions, confirm fraud proof validation holds, then set the One window.
V3.10 also packages stability improvements and security fixes. Offchain Labs recommends upgrading as soon as possible, independent of the ArbOS 60 timeline. If you operate any Arbitrum node, the security fixes are reason enough to move now.
The consensus-v60-rc.5 module is worth reading separately. It's a WASM fraud proof consensus version, and the release says directly it isn't a good version to run a node on. The WAVM module root is set at 0x7a9e6a77...cbb57 for chain validators. The operator node image is separate: offchainlabs/nitro-node:v3.10.0-b1cf6db.
Updating a WAVM module root isn't a routine patch. It pins the fraud proof program version to chain state. Once ArbOS 60 activates on One, any disputed transaction will be validated against this root. That's the deeper reason for staging through Sepolia first.
The tradeoff is time for confidence. One operators wait longer, but they get a live testnet run before their own window opens. When the One date drops, expect a similar deadline at mainnet scale. Missing the window on One affects more operators than Sepolia does.
If you run a Sepolia node, May 18 at 17:00 UTC is the clock. Watch the Offchain Labs GitHub for the One announcement after.
Offchain Labs' staged approach is the right call for a WAVM module root change, but holding the One date more than one week past May 18 Sepolia confirmation would signal the rc.5 build surfaced something the testnet was supposed to catch.
If Offchain Labs hasn't published an Arbitrum One ArbOS 60 activation date by June 1, 2026, assume the May 18 Sepolia run surfaced something that needs fixing before mainnet.
Primary links and supporting reads used by the desk for this story.
Forward this.
