# Upgrade 18 Protocol upgrade

> Notice date: March 11, 2026
>
> Target Network: GIWA Testnet (Sepolia)

## Overview

GIWA Chain will apply the Upgrade 18 protocol update from the OP Stack. This upgrade includes enhancements to fault proof security through dual implementation support and improvements to the internal contract structure.

{% hint style="info" %}
This is a L1 smart contract-level update, not a hardfork.
{% endhint %}

## Schedule

* Testnet (Sepolia): March 13, 2026

{% hint style="info" %}
The actual time may vary depending on network conditions and block timing.
{% endhint %}

## What's changing

* **Dual Fault Proof support**: A new Kona-based (Rust) fault proof implementation is added alongside the existing Cannon-based system, strengthening the overall security and reliability of the fault proof layer.
* **Dispute Game improvements**: Internal contract structure has been optimized, reducing gas costs related to dispute games.

## For Developers

If your application directly queries on-chain fault proof data, note that a new dispute game type (`CANNON_KONA`) has been added.

## Learn more

Want to learn more about Upgrade 18? Check out the [OP Stack documentation](https://docs.optimism.io/notices/archive/upgrade-18).


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