Problem description
The policy form field in your PostObject request is missing the required conditions parameter.
Causes
A PostObject request requires a policy form field containing expiration and conditions. If conditions is absent, OSS rejects the request even when expiration is present and valid.
Examples
The following policy is invalid because it omits conditions:
{
"expiration": "2023-02-19T13:19:00.000Z"
}Solutions
Include both expiration and conditions in your policy:
{
"expiration": "2023-02-19T13:19:00.000Z",
"conditions": [
["content-length-range", 0, 1048576000]
]
}The example above restricts the upload size to a maximum of 1,048,576,000 bytes using the content-length-range condition.
References
Appendix: Policy — full reference for the
policyform field structureAdd signatures on the client by using JavaScript and upload data to OSS — end-to-end form upload guide
Errors and troubleshooting methods of PostObject — other common PostObject errors