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General·HTTP 428·API

Precondition required

precondition_required

This change must name the version it was made from, in an If-Match header, and the request had none.

What this means​

The request replaces something other people may be editing too, so the API only takes it with the version you read.

How to fix it​

Read the resource, then send the change with the version you read (its revision or ETag) in the If-Match header.

Retry behavior​

Retry with the If-Match header. Without it the request gets the same answer.

How it appears in the response​

ComputeSphere returns errors as RFC 7807 Problem Details. The type field is the docs URL for this page — switch on code in your client.

{
  "type":    "https://computesphere.com/docs/errors/precondition_required",
  "title":   "Precondition required",
  "status":  428,
  "code":    "precondition_required",
  "detail":  "This change must name the version it was made from, in an If-Match header, and the request had none.",
  "instance": "/v2/…",
  "request_id": "f47ac10b-58cc-4372-a567-0e02b2c3d479",
  "trace_id":   null
}

The Content-Type header is application/problem+json. On field-level validation errors a non-empty errors[] array also appears, each entry carrying a docs_url to its error code's page.