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HTTP_STATUS_PRECOND_FAILED
It is commonly returned for conditional headers such as If-Match, If-None-Match, If-Unmodified-Since, or WebDAV conditional requests. The resource may have changed since the client last read it.
Fetch the current representation and validators before retrying. Do not discard concurrent changes by sending an unconditional overwrite unless that behavior is intentional.
Operational meaning of HTTP 412 for HTTP_STATUS_PRECOND_FAILED
HTTP 412 (HTTP_STATUS_PRECOND_FAILED) is a client-error response. AllStat records its meaning as “412 Precondition Failed”. For HTTP_STATUS_PRECOND_FAILED, interpret it with the request method, selected representation, response headers, and the specification or product that defines the code; the number alone does not prove that application work completed.
Client and server handling for HTTP_STATUS_PRECOND_FAILED
- Treat HTTP_STATUS_PRECOND_FAILED as a condition visible at the request boundary; inspect authentication, syntax, preconditions, routing, and resource state before retrying.
- For HTTP_STATUS_PRECOND_FAILED, preserve the response body and challenge or retry-related headers because they often carry the actionable reason.
- For HTTP_STATUS_PRECOND_FAILED, automatic retry is safe only when the method and status contract allow it and the request has been corrected.
For telemetry, record HTTP 412, method, authority, route template rather than secrets, response headers relevant to caching or retry, latency, upstream identity, and whether the response originated at the application or an intermediary.
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