iOS POST 上传图片时 返回status code 为203，之前都是正常，今天突然返回这个，但是上传是成功的

iOS POST 上传图片时 返回status code 为203，之前都是正常，今天突然返回这个，但是上传是成功的。以前都是成功返回200，现在在失败里返回203，返回信息如下：
Domain=com.alamofire.error.serialization.response Code=-1016 "Request failed: unacceptable content-type: application/xml" UserInfo={com.alamofire.serialization.response.error.response= { URL: http://meikemeiyin.oss-cn-beijing.aliyuncs.com/ } { status code: 203, headers {

Connection = "keep-alive";
"Content-Length" = 236;
"Content-Type" = "application/xml";
Date = "Tue, 30 Aug 2016 08:29:50 GMT";
Etag = "\"732A789F6839B2B482FC3F5A50B7D2FB\"";
Server = AliyunOSS;
"x-oss-hash-crc64ecma" = 287790314455018898;
"x-oss-request-id" = 57C543FD6FF1C54B1986154D;
"x-oss-server-time" = 285;

} }, NSErrorFailingURLKey=http://meikemeiyin.oss-cn-beijing.aliyuncs.com/, com.alamofire.serialization.response.error.data=<3c3f786d 6c207665 7273696f 6e3d2231 2e302220 656e636f 64696e67 3d225554 462d3822 3f3e0a3c 4572726f 723e0a20 203c436f 64653e43 616c6c62 61636b46 61696c65 643c2f43 6f64653e 0a20203c 4d657373 6167653e 4572726f 72207374 61747573 203a2034 30332e3c 2f4d6573 73616765 3e0a2020 3c526571 75657374 49643e35 37433534 33464436 46463143 35344231 39383631 3534443c 2f526571 75657374 49643e0a 20203c48 6f737449 643e6d65 696b656d 65697969 6e2e6f73 732d636e 2d626569 6a696e67 2e616c69 79756e63 732e636f 6d3c2f48 6f737449 643e0a3c 2f457272 6f723e0a>, NSLocalizedDescription=Request failed: unacceptable content-type: application/xml}
现在我们后台看到的是图片上传成功了，但是为什么会返回203呢？