> ## Documentation Index
> Fetch the complete documentation index at: https://docs.letmepost.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# pinterest.video.upload_failed

> The S3 multipart upload Pinterest handed us back rejected the bytes.

## What it checks

After `POST /v5/media` returns a presigned S3 endpoint + form-field bag, the publisher streams the video bytes to that endpoint as `multipart/form-data`. S3 returns 204 on success — anything else surfaces here verbatim.

## Why

The most common causes are signed-URL clock skew, a mime mismatch between what we declared and what we sent, or the registered slot expiring before the upload finished. S3 returns XML on errors; we pass the body through so the AWS-style error code is visible.

## Failure response

```json theme={"system"}
{
  "error": {
    "code": "platform_rejected",
    "rule": "pinterest.video.upload_failed",
    "platform": "pinterest",
    "message": "pinterest rejected the post: <Error>...",
    "remediation": "Pinterest's S3 upload rejected the bytes. Common causes: signed-URL clock skew, file mime mismatch, or the file size exceeded the registered slot. Retry; if it persists the registered slot has expired.",
    "platformResponse": {
      "status": 403,
      "body": "<Error><Code>SignatureDoesNotMatch</Code>...</Error>"
    }
  }
}
```

## Remediation

* Retry the publish. The publisher re-registers a fresh slot on each attempt, so an expired one self-heals.
* If `SignatureDoesNotMatch` repeats, check your server's clock — significant drift makes presigned URLs reject.
* If the body mentions an "EntityTooLarge" or similar size error, the file may be larger than what was registered; preflight should already catch this via [`pinterest.video.size_max`](/preflight/pinterest-video-size_max).

## Related

* [`pinterest.media.register_failed`](/preflight/pinterest-media-register_failed)
* [`pinterest.video.size_max`](/preflight/pinterest-video-size_max)