AFHTTPRequestOperationManager Get request failed,Error Domain=AFNetworkingErrorDomain Code=-1016

I send a GET request to the url like this : `https://test.com/app/login?json={"user":"test@gmail.com","password":"test"}` but return this error: ``` Error Domain=AFNetworkingErrorDomain Code=-1016 "Request failed: unacceptable content-type: text/plain" UserInfo=0x9ad3520 {NSErrorFailingURLKey=https://test.com/app/login?json=%7B%22user%22:%22test@gmail.com%22,%22password%22:%22test%22%7D, AFNetworkingOperationFailingURLResponseErrorKey= { URL: https://test.com/app/login?json=%7B%22user%22:%22test@gmail.com%22,%22password%22:%22test%22%7D } { status code: 200, headers { "Cache-Control" = "max-age=900"; Connection = "Keep-Alive"; "Content-Length" = 6116; "Content-Type" = "text/plain; charset=UTF-8"; Date = "Wed, 15 Jan 2014 09:14:22 GMT"; Expires = "Wed, 15 Jan 2014 09:29:22 GMT"; "Keep-Alive" = "timeout=2, max=100"; Server = "Apache-Coyote/1.1"; "Set-Cookie" = "APP-SESSION-ID=xxxxxxxxxxxxxxxx; Path=/app/; HttpOnly, APP-ROUTE-ID=.app1_node2; path=/, API-ROUTE-ID=.app1_node2; path=/"; } } , NSLocalizedDescription=Request failed: unacceptable content-type: text/plain} ``` Here is my code, and I have added percent escapes with NSUTF8StringEncoding. ``` manager = [AFHTTPRequestOperationManager manager]; manager.responseSerializer = [AFHTTPResponseSerializer serializer]; [manager GET:url parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) { } failure:^(AFHTTPRequestOperation *operation, NSError *error) { }]; ```