调用其他的V3接口是正常的，但调用这个接口返回如下内容：

{"code":"SIGN_ERROR","detail":{"detail":{"issue":"sign not match"},"field":"signature","location":"authorization","sign_information":{"method":"POST","sign_message_length":89,"truncated_sign_message":"POST\n/v3/marketing/favor/media/image-upload\n1586354275\n7f6ae5e1619f41b1ad1172815a5992a7\n\n","url":"/v3/marketing/favor/media/image-upload"}},"message":"错误的签名，验签失败"}

签名为如下：

WECHATPAY2-SHA256-RSA2048 mchid="1321550501",nonce_str="7f6ae5e1619f41b1ad1172815a5992a7",signature="nbIS99Y7bfkkHIVSSleSqLMeNYvnGdkuU8DOJlpkmI9Q+8ydxnlQ9m/h5wwc4Drr1A9IQko4elMDb2RtcJNKm7CNx6AZWjpv9v8g5jhq2iJHYJzlcTlicoBssJ0dpj3/GM4wUDE2cD744L7FpeAHfeSzzI2K9u4TqybOznpPwv2KRs8f+xEOb3sWRDfaef3TiD4X4vikcp6dn+d42bifRhxCBl7oFVJkI3hjrwTB7Y8DQRpncmylnNBPAb6D7iCklkpTAwEqQQuSld1SmuFH3VjzEuRK5mO64gJYGsJ5piOGfAiUbT0eGQIG0wKJAF1e3hGroh/X7PlC0Fl7k0h1dw==",timestamp="1586354275",serial_no="4626AEBAD62EE15F50EFFB126384E24F56DB13C6"

不知是image图片文件的sha256计算错误还是签名计算错误。谢谢！