precondition_failed error (HTTP 412)

HTTP status: 412 Precondition Failed

You sent an If-Match header, and the resource no longer has that ETag. It changed after you read it, so your write was refused and nothing from your request was saved. On a GET, the resource isn’t returned.

You only get this error when you send If-Match. A PUT without the header (or with If-Match: *) applies unconditionally, and a write that loses a race at the same moment gets conflict instead.

Common causes

• Another user, token or the dashboard updated the resource between your GET and your PUT.
• Another endpoint changed something in the resource’s body. The ETag covers all of it, so toggling a flag, archiving it, or setting its owner, expiry, permanence or removal PR changes the flag’s ETag, and a toggle also changes its environment config and targeting ETags.
• On a targeting PUT, a rule in that environment was added, deleted, edited or reordered. The targeting ETag covers the whole rule set.
• On a webhook, a delivery failed. The failure count is part of the body, so each failed delivery changes the ETag. Retrying right after a fresh GET almost always works.
• Your token’s role changed. The ETag covers _actions, which depends on the role.
• The resource has no ETag: a list, or an environment in which the flag has never been configured.
• The header doesn’t hold an ETag this resource issues: a weak tag (W/"80857c9ec8c53314"), an unquoted value, or a list of several tags.

How to fix

1. GET the resource again and read its ETag response header.
2. Check whether your change still makes sense against what’s there now, and re-apply it to the fresh copy.
3. Send the PUT again with the new ETag, for example If-Match: "80857c9ec8c53314".

See Conditional writes for which endpoints support If-Match.

Example

{
  "error": "precondition_failed",
  "message": "The resource changed since the ETag you sent. GET it again, then retry with the new ETag.",
  "docs_url": "https://featureflip.io/docs/management-api/errors/precondition_failed"
}