Problem description
The policy form field in a PostObject request is missing.
Causes
You initiated a PostObject request that included the signature, but the policy form field is missing.
Examples
You initiated a PostObject request that included the signature authentication in the form field, but the policy form field is missing.
Solutions
The policy form field in a PostObject request is used to verify the validity of the request. The policy value is a JSON text that is encoded in UTF-8 and Base64. This value specifies the conditions that a PostObject request must meet. If you want to calculate the signature when you upload objects by calling the PostObject operation, you must include the policy form field in the request.
For more information, see PostObject.