# Network Upgrades
Source: https://docs.chain.link/cre/network-upgrades
Last Updated: 2026-10-01

> For the complete documentation index, see [llms.txt](/llms.txt).

Blockchain networks periodically upgrade their protocol. Most upgrades do not affect CRE workflows, but some change how transactions are priced or executed. This page tracks upcoming upgrades that may require action from workflow developers.

## Ethereum Glamsterdam

Ethereum is upgrading to [Glamsterdam](https://ethereum.org/roadmap/glamsterdam/) during Q4 2026. The Ethereum Sepolia upgrade is scheduled for 6 October 2026 at 13:53:36 UTC; Hoodi and Mainnet timings are still to be confirmed.

Glamsterdam changes the gas model of the chain. **You do not need to do anything unless your workflow sets a gas limit**, in which case see [Preparation](#preparation) below.

### Timelines

| Network              | Timing                                         | Impact                                                                                  |
| -------------------- | ---------------------------------------------- | --------------------------------------------------------------------------------------- |
| **Ethereum Sepolia** | 6 October 2026, 13:53:36 UTC                   | Workflows writing to Ethereum Sepolia may fail 30 minutes before and after the upgrade. |
| **Ethereum Hoodi**   | Q4 2026 (will be confirmed closer to the time) | Workflows writing to Ethereum Hoodi may fail 30 minutes before and after the upgrade.   |
| **Ethereum Mainnet** | Q4 2026 (will be confirmed closer to the time) | Workflows writing to Ethereum Mainnet may fail 30 minutes before and after the upgrade. |

> **NOTE: Writes may fail during the upgrade window**
>
> Onchain writes to the affected network may fail for roughly 30 minutes before and 30 minutes after each upgrade. If a write fails during this window, retry it after the upgrade completes.

### Preparation

If your workflows set a gas limit, you may need to adjust it once the hardfork takes effect. The new gas limit value depends on how much storage versus compute your transactions use, so we cannot advise on how to adjust your limits.

To best prepare:

1. **Ahead of the Ethereum Sepolia upgrade**, update your workflows to add extra gas headroom or unset the gas limit, and confirm they still succeed.
2. **After the Ethereum Sepolia upgrade on 6 October 2026**, confirm whether your workflow's transactions still succeed. If they do, no more action is needed. If you still have a gas limit set and your transactions are reverting due to out of gas, increase your gas limit well above the previous Fusaka limit of 16,777,216.
3. **Ahead of the Ethereum Hoodi and Mainnet upgrade** (date to be confirmed in Q4 2026), apply the same steps as Ethereum Sepolia to minimize impact to your workflows.

For details on configuring gas limits in your workflows, see [Configuring gas limits](/cre/guides/workflow/using-evm-client/onchain-write/using-write-report-helpers#configuring-gas-limits) and [Writing data onchain](/cre/guides/workflow/using-evm-client/onchain-write/writing-data-onchain).

## Learn more

- [Supported Networks](/cre/supported-networks) — Networks available for simulation and production
- [Writing Data Onchain](/cre/guides/workflow/using-evm-client/onchain-write/writing-data-onchain) — Configure gas limits for onchain writes
- [Release Notes](/cre/release-notes) — What's new in CRE