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Maintenance Mode allows administrators to reduce write operations to a minimum while maintenance tasks are performed. The main goal is to block all external actions that change the internal state, including the PostgreSQL database, but especially files, Git repositories, Container repositories, and so on.
Once Maintenance Mode is enabled, in-progress actions finish relatively quickly since no new actions are coming in, and internal state changes are minimal.
further degraded for a much shorter period of time than might otherwise be needed. For example, stopping cron jobs and draining queues should be fairly quick.
Maintenance Mode allows most external actions that do not change internal state. On a high-level, HTTP `POST`, `PUT`, `PATCH`, and `DELETE` requests are blocked and a detailed overview of [how special cases are handled](#rest-api) is available.
In some cases, the visual feedback from an action could be misleading, for example when starring a project, the **Star** button changes to show the **Unstar** action, however, this is only the frontend update, and it doesn't take into account the failed status of the POST request. These visual bugs are to be fixed [in follow-up iterations](https://gitlab.com/gitlab-org/gitlab/-/issues/295197).
If there are [LDAP syncs](../auth/ldap/index.md) scheduled for that time, they fail since user creation is disabled. Similarly, [user creations based on SAML](../../integration/saml.md#general-setup) fail.
All read-only Git operations continue to work, for example
`git clone` and `git pull`. All write operations fail, both through the CLI and Web IDE with the error message: `Git push is not allowed because this GitLab instance is currently in (read-only) maintenance mode.`
For most JSON requests, `POST`, `PUT`, `PATCH`, and `DELETE` are blocked, and the API returns a 403 response with the error message: `You cannot perform write operations on a read-only instance`. Only the following requests are allowed:
`POST /api/graphql` requests are allowed but mutations are blocked with the error message `You cannot perform write operations on a read-only instance`.
### Continuous Integration
- No new jobs or pipelines start, scheduled or otherwise.
- Jobs that were already running continue to have a `running` status in the GitLab UI,
even if they finish running on the GitLab Runner.
- Jobs in the `running` state for longer than the project's time limit do not time out.
- Pipelines cannot be started, retried or canceled. No new jobs can be created either.
[Incident management](../../operations/incident_management/index.md) functions are limited. The creation of [alerts](../../operations/incident_management/alerts.md) and [incidents](../../operations/incident_management/incidents.md#incident-creation) are paused entirely. Notifications and paging on alerts and incidents are therefore disabled.
- [Development feature flags](../../development/feature_flags/index.md) cannot be turned on or off through the API, but can be toggled through the Rails console.
In the use case of [a planned failover](../geo/disaster_recovery/planned_failover.md), a few writes in the primary database are acceptable, since they are replicated quickly and are not significant in number.
However, during a planned failover, we [ask users to turn off cron jobs that are not related to Geo, manually](../geo/disaster_recovery/planned_failover.md#prevent-updates-to-the-primary-site). In the absence of new database writes and non-Geo cron jobs, new background jobs would either not be created at all or be minimal.
