Hi Lynn,
Which HTTP headers do you send? (apart from the default content-types that Mendix adds automatically)
For example: do you have a ‘Accept:application/json’ header set for the response from the server?
Request content for POST request to https://qyapi.weixin.qq.com/cgi-bin/media/upload?access_token=xxx&type=file HTTP/1.1
Accept: application/json
Content-Type: multipart/form-data; boundary="----=_Part_2_1709568546.1638275702857"
------=_Part_2_1709568546.1638275702857
Content-Type: application/octet-stream
Content-Disposition: form-data; name="media"; filename="wework.txt.txt"
mytext
------=_Part_2_1709568546.1638275702857--
Response content for POST request to https://qyapi.weixin.qq.com/cgi-bin/media/upload?access_token=xxx&type=file
HTTP/1.1 200 OK
Server: nginx
Date: Tue, 30 Nov 2021 12:35:03 GMT
Content-Type: application/json; charset=UTF-8
Content-Length: 171
Connection: keep-alive
Error-Code: 44001
Error-Msg: empty media data, hint: [1638275703408543409302529], from ip: 20.197.0.110, more info at https://open.work.weixin.qq.com/devtool/query?e=44001
{"errcode":44001,"errmsg":"empty media data, hint: [1638275703408543409302529], from ip: 20.197.0.110, more info at https://open.work.weixin.qq.com/devtool/query?e=44001"}