409

Conflict

The server deems the request to be invalid as it is in conflict with the current stats of the target resource. The user may be able to resolve the conflict and make the request again. The server sends back information about the source of conflict. These typically occur in PUT requests.

Use Case

A user is trying to update a shared resource, but the changes they made are in conflict with some changes made by another user's request. So, the server responds with a 409 code, indicating the request cannot be served with some information about the source of the conflict.