412 Precondition Failed

The server does not meet one of the preconditions that the requester put on the request.

POST, creating entities
412 Precondition Failed if e.g. the resource wouldn’t statisfy some uniqueness criterion
PATCH, mutating entities
412 Precondition failed, when failing to honour If-Match or If-Unmodified-Since headers.
DELETE, destroying entities
412 Precondition Failed
Return codes and errors
412 Precondition failed: resource versioning issues.