4xx Client errors
409 Conflict
The request conflicts with the current state of the resource.
Common causes
- Two edits to the same record at once.
- Creating something that already exists.
How to fix it
- Reload the latest version, then try the change again.
Find out the moment your site returns 409
Spot Downtime monitors count this as down and alert you, since visitors see an error. (The public “Is it down?” checker treats 4xx answers from big sites as online, because many refuse automated requests.)