> ## Documentation Index
> Fetch the complete documentation index at: https://docs.optimism.io/llms.txt
> Use this file to discover all available pages before exploring further.
# Upgrade 18 - Cannon + Kona and Custom Gas Token v2
> Learn how to prepare for Upgrade 18.
Upgrade 18 is a proposed network upgrade for OP Stack chains, which **introduces support for kona-proof as an alternate fault proof program**, introduces **Custom Gas Token v2 (CGT v2)** for new OP Stack chains that want to use a non-ETH native fee currency, and a creator pattern dispute game refactor.
Upgrade 18 is purely a smart contract upgrade. There are no hardforks activating during this upgrade.
## What's included in Upgrade 18
Upgrade 18 introduces the following changes:
* **Cannon + Kona game type support:** adds a new fault dispute game type `CANNON_KONA` (8) alongside `CANNON` (0) increasing the redundancy and diversity in the fault proof layer. This is a Rust-based fault proof implementation where `kona-client` (`kona-node` + `op-reth`) can operate alongside `op-program` (`op-node` + `op-geth`). Both game types use Cannon as the FPVM and the same dispute game implementation (`FaultDisputeGame.sol`). This upgrade does not change the respected game type.
* **Custom Gas Token v2 (CGT v2):** introduces an `isCustomGasToken()` flag and two new predeploys (`NativeAssetLiquidity` and `LiquidityController`) to support non-ETH native fee currencies configured at genesis (available in `op-contracts/v6.0.0`).
* **Creator Pattern Dispute Game Refactor:** simplifies the chain deployment by introducing clone-with-immutable-arguments (CWIA) for dispute game contracts. This change removes the need for chain-specific deployments, reducing operational overhead while preserving safety and upgradeability across chains, and reducing gas costs to ensure all operations stay below the EIP-7825 transaction gas limit cap.
## Breaking Changes
### `OPCM`: new `OpChainConfig` parameters for the Cannon + Kona game type
Upgrade 18 updates the upgrade parameters so `OpChainConfig` include:
* `cannonKonaPrestate` (must be a valid `cannon64-kona` prestate hash) and
* `cannonPrestate` (must be a valid `cannon64` prestate hash)
Both prestates must be canonical hashes from the Superchain Registry `standard-prestates.toml` and must embed an up-to-date chain config for your chain.
After upgrade, `DisputeGameFactory` will have implementations set for:
* `CANNON` (0)
* `PERMISSIONED` (1)
* `CANNON_KONA` (8)
Games of any type can be created after upgrade, but withdrawals continue to use the respected game type.
For chains running only permissioned proofs: cannon+kona will not be deployed and `cannonKonaPrestate` is ignored.
### Custom Gas Token v2: ETH value is rejected when enabled
When CGTv2 is enabled at genesis, `isCustomGasToken()` is set on L1 and L2:
* **On L1** (`SystemConfig`): `OptimismPortal`, `L1CrossDomainMessenger`, and `L1StandardBridge` reject transactions containing ETH value (`msg.value`).
* **On L2** (`L1Block`): ETH-related operations are blocked in `L2ToL1MessagePasser`, `L2CrossDomainMessenger`, `L2StandardBridge`, and fee vaults.
ETH bridging routes through L1-WETH as an ERC-20 wrapper when CGT is enabled.
There is currently no migration path from legacy CGT to CGT v2.
## For chain operators
Update the following components:
| Component | Version | Notes |
| ---------------- | ------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `op-challenger` | [`op-challenger/v1.9.0`](https://github.com/ethereum-optimism/optimism/releases/tag/op-challenger%2Fv1.9.0) | Must be updated **prior** to the upgrade for permissionless fault proof chains. |
| `op-dispute-mon` | [`op-dispute-mon/v1.5.0`](https://github.com/ethereum-optimism/optimism/releases/tag/op-dispute-mon%2Fv1.5.0) | Must be updated **prior** to the upgrade for permissionless fault proof chains. |
| `op-contracts` | `op-contracts/v6.0.0` | [op-contracts/v6.0.0-rc.1](https://github.com/ethereum-optimism/optimism/releases/tag/op-contracts%2Fv6.0.0-rc.1) will be finalized if it gets governance approval. |
### For permissionless fault proof enabled chains
Chains running permissionless fault proofs must ensure challengers are Kona-ready and that both `CANNON` and `CANNON_KONA` are configured correctly.
Optimism will complete the onchain cannon+kona deployment for chains managed by the Optimism Security Council.
However, off-chain components must still be configured by operators to support cannon-kona games.
If you are a permissionless FP enabled chain not included in the prepared set, you must perform all steps below yourself.
The absolute prestate is generated with the [op-program/v1.9.0-rc.1](https://github.com/ethereum-optimism/optimism/tree/op-program/v1.9.0-rc.1). You can use this new absolute prestate `0x033c000916b4a88cfffeceddd6cf0f4be3897a89195941e5a7c3f8209b4dbb6e` for the following chains:
* Mainnet and Sepolia: `OP`, `Base`, `Ink`, `Soneium`, and `Unichain`
You can verify this absolute prestate by running the following command in the root of the monorepo on the `op-program/v1.9.0-rc.1` tag:
```shell theme={null}
make reproducible-prestate
```
This will output the calculated prestates, the tail end of the output should look like this:
```shell theme={null}
-------------------- Production Prestates --------------------
Cannon64 Absolute prestate hash:
0x033c000916b4a88cfffeceddd6cf0f4be3897a89195941e5a7c3f8209b4dbb6e
...
```
* The "Cannon64" hash is the 64-bit prestate.
Verify that your target prestate was calculated as expected and matches the corresponding entry in
[standard-prestates.toml](https://github.com/ethereum-optimism/superchain-registry/blob/main/validation/standard/standard-prestates.toml).
The absolute prestate is generated with the [kona-client/v1.2.7](https://github.com/ethereum-optimism/kona/tree/kona-client/v1.2.7) (Note that Kona is currently being moved into the [ethereum-optimism/optimism repo](https://github.com/ethereum-optimism/optimism), but for building this release use the [op-rs/kona repo](https://github.com/op-rs/kona)). You can use this new absolute prestate `0x0323914d3050e80c3d09da528be54794fde60cd26849cd3410dde0da7cd7d4fa` for the following chains:
* Mainnet and Sepolia: `OP`, `Base`, `Ink`, `Soneium`, and `Unichain`
You can verify this absolute prestate by running the following commands in the root of the kona monorepo on the `kona-client/v1.2.7` tag:
```shell theme={null}
cd docker/fpvm-prestates
just cannon kona-client kona-client/v1.2.7 $(cat ../../.config/cannon_tag)
jq -r .pre ../../prestate-artifacts-cannon/prestate-proof.json
```
Verify that your target prestate was calculated as expected and matches the corresponding entry in
[standard-prestates.toml](https://github.com/ethereum-optimism/superchain-registry/blob/main/validation/standard/standard-prestates.toml).
During the previous step, you also generated the preimage of the absolute prestate, which is the op-program serialized into a binary file. You'll find the new cannon 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 `0x033c000916b4a88cfffeceddd6cf0f4be3897a89195941e5a7c3f8209b4dbb6e.bin.gz`.
You'll find the new kona cannon file at `prestate-artifacts-cannon/prestate.bin.gz`. Rename that file to have the absolute prestate hash as the filename so it looks like `0x0323914d3050e80c3d09da528be54794fde60cd26849cd3410dde0da7cd7d4fa.bin.gz`.
Upload those file to where you're storing your other absolute preimage files. This should be the location where you're pointing your `--prestates-url` at. The `op-challenger` will grab this file and use it when it needs to challenge games.
Ensure `op-challenger` is updated and configured to support Kona games.
Include `cannon-kona` in trace types:
```bash theme={null}
OP_CHALLENGER_TRACE_TYPE="cannon,cannon-kona,permissioned"
# or
--trace-type=cannon,cannon-kona,permissioned
```
Upload new preimage files and ensure they're available for the challenger.
If both preimage files are uploaded at the same location:
```bash theme={null}
--prestates-url=
```
If stored separately:
```bash theme={null}
--cannon-prestates-url=
--cannon-kona-prestates-url=
```
If not using the standard OP Labs `op-challenger` Docker image, set the `kona-host` binary path:
```bash theme={null}
OP_CHALLENGER_CANNON_KONA_SERVER=/path/to/kona-host
# or
--cannon-kona-server=/path/to/kona-host
```
Build `kona-host` from the same release as the configured cannon-kona prestate.
## Execute the L1 Contract Upgrade
Once your `op-challenger` is ready (and Kona-ready if permissionless), you can execute the upgrade transaction. This should be done by making a delegatecall to the `upgrade()` function of the OP Contract Manager at the address listed in [the registry](https://github.com/ethereum-optimism/superchain-registry/blob/main/validation/standard/standard-versions-mainnet.toml).
Please simulate and validate the expected output prior to executing the transaction.