---
set: 4
code: 412
title: Precondition Failed
references:
    "Rails HTTP Status Symbol": ":precondition_failed"
    "Go HTTP Status Constant": "http.StatusPreconditionFailed"
---

One or more conditions given in the request header fields evaluated to false
when tested on the server.

This response code allows the client to place preconditions on the current
resource state (its current representations and metadata) and, thus, prevent the
request method from being applied if the target resource is in an unexpected
state.

---

* Source: [RFC7232 Section 4.2][1]

[1]: <http://tools.ietf.org/html/rfc7232#section-4.2>