HTTP 412 Precondition Failed means one or more conditions specified in the request headers (If-Match, If-Unmodified-Since, If-None-Match) evaluated to false. The server will not perform the requested operation because the preconditions are not met.
The If-Match header contained an ETag that does not match the current version of the resource — someone else modified it.
The If-Unmodified-Since condition failed because the resource was modified after the specified date.
GET the resource to obtain the latest ETag or Last-Modified date, then retry with updated precondition headers.
Compare the current resource state with your intended changes and merge if necessary.
If you do not need optimistic concurrency control, remove the conditional headers.