Python，请求无法解码数据？

Question

我想知道导致以下错误的原因是数据发送到的网站还是脚本问题？

我发送了以下POST请求：

import requests 

session = requests.session() 
url = "private url" 
headers = {"Content-Type": "Application/json"} 
session.headers.update(headers) 
payload = {"test": "test", "quantity": 1} 
output = session.post(url, data=payload) 
print(output.text)

输出：

  

{"_v":"14.6","fault":{"type":"InvalidMessageException","message":"An error occurred while decoding the request, the body was 'test=test&quantity=1'."}