我收到{“错误”：“invalid_client”，“错误描述”：“客户端身份验证失败”} 401响应。我确实设法获得了用户同意（docs：https://developer.ebay.com/api-docs/static/oauth-authorization-code-grant.html），方法是手动访问URL并登录到我的帐户：

import requests, urllib, base64

my_AppID = "someAppID"
my_Ru_Name = "someRuName"
scope = "https://api.ebay.com/oauth/api_scope/sell.fulfillment"
scope = urllib.parse.quote_plus(scope)

url = f"""https://auth.ebay.com/oauth2/authorize?
client_id={my_AppID}&
redirect_uri={my_Ru_Name}&
response_type=code&
scope={scope}&"""

我打印了url字符串，并在浏览器中访问它，登录并“同意”。此页面显示“授权成功完成”。因此我从新重定向页面url中获取代码值。此后，我无法将授权代码交换为用户访问令牌：

my_CertID = "someCertID"
client_id = base64.b64encode(my_AppID.encode())
client_secret = base64.b64encode(my_CertID.encode())
auth_string = "Basic " + client_id.decode() + ":" + client_secret.decode()

consent_code = "v%521.1%25i..................jYw" # from the page's link after logging in
consent_code = urllib.parse.quote_plus(code)

headers = {"Content-Type": "application/x-www-form-urlencoded", "Authorization": auth_string}
data = {"grant_type": "authorization_code", "code": consent_code , "redirect_uri": Ru_Name}
url_token = "https://api.ebay.com/identity/v1/oauth2/token"

resp = requests.post(url_token, headers=headers, data=data)
print(resp.text)

# the response I get:
{"error":"invalid_client","error_description":"client authentication failed"}

我做错了什么？是请求部分？还是编码？
我对这一切都有点陌生，所以提前感谢！