# Upgrade 16a Protocol upgrade

> Notice date: November 10, 2025
>
> Target Network: GIWA Testnet (Sepolia)

## Overview

GIWA Chain will apply the **Upgrade 16a** protocol update from the OP Stack. This is a maintenance release that includes internal improvements to enhance system stability.

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Any withdrawals that have **not been finalized** before the upgrade will need to be **reproven** after the upgrade.
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## Schedule

* Testnet (Sepolia): *November 12, 2025*

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The actual time may vary depending on network conditions and block timing.
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## For Users

* If a withdrawal to L1 is **not yet finalized** when the upgrade is executed, the corresponding **withdrawal proof will be invalidated**.  In that case, you will need to **resubmit the withdrawal proof** after the upgrade completes.
* Withdrawals that are already **finalized** will **not** be affected.
* All assets (ETH and tokens) remain **safe**, and there is **no risk of loss**.

## For Developers

* Applications related to bridge withdrawals (e.g., withdrawal status trackers, bridge UIs, etc.) should account for possible **temporary withdrawal proof invalidation** during the upgrade window.
* If your app monitors withdrawal proofs on L1, make sure it can detect invalidated proofs and **retry** accordingly.
* No changes are required for smart contracts already deployed on the GIWA network.

## Learn more

Want to learn more about Upgrade 16a?  Check out the [OP Stack documentation](https://docs.optimism.io/notices/archive/upgrade-16a#impact-summary).


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