The Isthmus hard fork for the Sepolia Superchain will be activated at Thu Apr 17 16:00:00 UTC 2025 (
1744905600
) and the Mainnet Superchain will be activated at Fri May 9 2025 16:00:01 UTC (1746806401
).
This is for all chains who have opted into the hard fork inheritance behavior.What’s included in Isthmus
Isthmus contains these main changes:- Implement Prague features on the OP Stack: This includes the EIPs that are relevant to the L2 that are being added to Ethereum with its Pectra activation. Learn more about this here.
- L2 Withdrawals Root in Block Header: This lowers the lift for chain operators by allowing them to run a full node to operate
op-dispute-mon
making it easier to guarantee the security of the fault proofs for the chains in the Superchain as the number of chains scales. Learn more about this here. - Operator Fee: A new component to the fee formula for the OP Stack which is a first step towards better resource pricing. This improves the OP Stack ability to support chains using Alt-DA or using ZK proving. Learn more about this here.
For chain operators
Chain operators must upgrade their nodes ahead of the activation times to a release that contains the Isthmus changes and has the activation times for their chains baked in, or set the activation times manually via overrides. The details are outlined in the node operator section below. Additionally, chain operators must updateop-batcher
to v1.12.0
and must update op-challenger
to v1.4.0
.
In addition to this, the L1 smart contract upgrades in upgrade 14 are required to utilize this new functionality.
For permissionless fault proof enabled chains
Chains running permissionless fault proofs will need to deploy new dispute game contracts with new absolute prestates. The new 64 bit version of cannon will be utilized moving forward. The Sepolia Superchain, will utilize op-program/v1.6.0-2. The following permissionless fault proof Sepolia chains are:Base Sepolia
, Ink Sepolia
, and OP Sepolia
.
1
Verify the new absolute prestate
As of upgrade 14, the 64 bit multi-threaded version of cannon is utilized.
0x03682932cec7ce0a3874b19675a6bbc923054a7b321efc7d3835187b172494b6
) for the following chains:- Sepolia: Base, Creator Chain, OP, Metal, Mode, Zora, Ethernity, Unichain, Ink, and Minato (Soneium)
op-program/v1.6.0-rc.2
tag:2
Upload your new preimage file
During the previous step, you also generated the preimage of the absolute prestate, which is basically the op-program serialized into a binary file. You’ll find that new file at
optimism/op-program/bin/prestate-mt64.bin.gz
. Rename that file to have the absolute prestate hash as the filename so it looks like 0x03682932cec7ce0a3874b19675a6bbc923054a7b321efc7d3835187b172494b6.bin.gz
.Upload that file to where you’re storing your other absolute preimage files. This should be the location where you’re pointing your --cannon-prestates-url
at. The op-challenger
will grab this file and use it when it needs to challenge games.3
Deploy new dispute game contracts
You will then take the absolute prestate and deploy new
FaultDisputeGame
and PermissionedDisputeGame
contracts with that value.4
Update the DisputeGameFactory
You will then need to update the
DisputeGameFactory
to point to the new FaultDisputeGame
and PermissionedDisputeGame
contracts by calling DisputeGameFactory.setImplementation
.5
Execute the upgrade
Once your
op-challenger
is ready with the new preimage, you can execute the “Set Dispute Game Implementation” transaction. Please simulate and validate that the expected output prior to executing the transaction.For node operators
Node operators will need to upgrade to the respective Isthmus releases before the activation dates. These following steps are necessary for every node operator:1
Update to the latest release
The releases contain both the Isthmus Mainnet and Sepolia Superchain activation timestamps.
2
Configure the Isthmus activation date
If you are operating a node for an OP Chain that has opted into the hardfork activation inheritance behavior and are utilizing the network flags, the Isthmus activation date is part of the
op-node
and op-geth
nodes. So, no action is needed for the sequencer after upgrading to the latest release. Please skip to Step 3: Verify Your Configuration.The following chains are included but are subject to change: Base Sepolia
, Creator Chain Testnet
, Ethernity Sepolia
, Ink Sepolia
, Lisk Sepolia
, Metal Sepolia
, Mode Sepolia
, Minato (Soneium) Sepolia
, OP Sepolia
, Unichain Sepolia
, and Zora Sepolia
.If you use custom genesis chain configuration, you need to set the
pragueTime
to the same value as the isthmusTime
. It is not automatically set, this happens by default for chains using the network flags and also when using the override flags.- Option 1: Set the activation time in the
rollup.json
forop-node
. You will still need to set theoverride.isthmus
flag inop-geth
if you use this option. Please note that the chain configuration file is subject to a stricter format and needs to contain thechain_op_config
outlined in theop-node/v1.11.0
release notes. - Option 2: Set the activation time via overrides (CLI) in both
op-node
andop-geth
. These will need to be set onop-node
andop-geth
for the sequencer and all other nodes.
3
Verify Your Configuration
Make the following checks to verify that your node is properly configured.
op-node
andop-geth
will log their configurations at startup- Check that the Isthmus time is set to
activation-timestamp
in the op-node startup logs - Check that the Isthmus time is set to
activation-timestamp
in the op-geth startup logs