conflict
409 · Conflicts with the current stateWhat happened
The request is valid but conflicts with the current state of the thing it is about.
What to do
Read detail — it says which state. Retrying the identical request will conflict identically until that state changes.
Is retrying worth it
No. Repeating the identical request will fail identically. Something has to change first, and the line above says what.
Reading the response
Errors are RFC 9457 problem details. Switch on code, which is stable, and never on title, which is written for a person and may be reworded or translated. detail carries the specifics of this occurrence, and meta carries whatever the client needs to render the right state instead of a dead end.
Every response also carries an X-Request-Id header. Quote it if you report something — it is what lets us find the exact request.