Problem description
The format of the form fields in the PostObject request is invalid.
Causes
You initiated a PostObject request. However, the format of the form fields in the request is invalid. Possible causes:
The file field is not the last field. The last field must be the file field.
The names of the form fields are not case-sensitive. The names of the form fields must be case-sensitive, such as Policy, Key, file, OSSAccessKeyId, and Content-Disposition.
Examples
The error is returned because the file field is not the last field.
POST / HTTP/1.1
Host: oss-example.oss-cn-hangzhou.aliyuncs.com
Content-Length: 6443500495
Date: Sat, 18 Feb 2023 05:17:02 GMT
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryW0DET1iaBMeAOBg3
Host: example-bucket.oss-cn-hangzhou.aliyuncs.com
------WebKitFormBoundaryW0DET1iaBMeAOBg3
Content-Disposition: form-data; name="name"
big.img
------WebKitFormBoundaryW0DET1iaBMeAOBg3
Content-Disposition: form-data; name="key"
${filename}
------WebKitFormBoundaryW0DET1iaBMeAOBg3
Content-Disposition: form-data; name="policy"
eyJleHBpcmF0aW9uIjoiMjAyMy0wMi0xOFQxMzoxOTowMC4wMDBaIiwiY29uZGl0aW9ucyI6W1siY29udGVudC1sZW5ndGgtcmFuZ2UiLDAsMTA0ODU3NjAwMF1dfQ==
------WebKitFormBoundaryW0DET1iaBMeAOBg3
Content-Disposition: form-data; name="file"; filename="big.img"
Content-Type: application/octet-stream
***
------WebKitFormBoundaryW0DET1iaBMeAOBg3
Content-Disposition: form-data; name="OSSAccessKeyId"
LTAI5tMw****
------WebKitFormBoundaryW0DET1iaBMeAOBg3
Content-Disposition: form-data; name="success_action_status"
200
------WebKitFormBoundaryW0DET1iaBMeAOBg3
Content-Disposition: form-data; name="signature"
miAoLVohS5*****WEXyC3wVecaQ=
------WebKitFormBoundaryW0DET1iaBMeAOBg3--Solutions
Make sure that the file field is the last field in the PostObject request and the format of the form fields in the request body is valid.
References
For more information about the PostObject operation, see PostObject.
For information about how to transfer data from the web client to OSS by using form upload, see Add signatures on the client by using JavaScript and upload data to OSS.
For information about common errors and troubleshooting methods of the PostObject operation, see Errors and troubleshooting methods of PostObject.