---
title: Maintenance Mode
---

:::info Availability

Maintenance mode was introduced in Unleash 4.21.0.

:::

Unleash maintenance mode is a feature that lets administrators put Unleash into a mostly read-only mode. While Unleash is in maintenance mode: 
- Unleash users **can not change any configuration settings**
- Unleash's APIs will not allow you to persist any changes

However, any metrics sent to Unleash from client SDKs are still processed, so this mode does not have any effect on client SDKs.

Maintenance mode is particularly useful during important events when any accidental or deliberate changes the feature/strategy configurations could lead to issues.

## Maintenance mode configuration

Maintenance mode is controlled from the "maintenance" section of the Unleash admin configuration page.

![Maintenance mode being toggled on](/img/maintenance-config.png)

When maintenance mode is enabled, a warning banner appears at the top of the Unleash dashboard, indicating that any changes made during this period will not be saved and may result in errors.

![Maintenance mode banner when maintenance mod is toggled on](/img/maintenance-banner.png)
