Error Domain=NSPOSIXErrorDomain Code=100 "Protocol error"

Question

I am trying to call a service using Alamofire using a .get method. The request has nothing special no parameters just an Authorization header.

I am going a bit mad here because to request works fine when I run it on postman with the same URL and Authorization token, but when I run my app code with Alamofire it returns this error:

Error Domain=NSPOSIXErrorDomain Code=100 "Protocol error" UserInfo={NSErrorPeerAddressKey={length = 16, capacity = 16, bytes = 0x100201bbd83ad0b10000000000000000}, _kCFStreamErrorCodeKey=100, _kCFStreamErrorDomainKey=1}

I am using:

Alamofire.request("https://myserverURL", method: .get, parameters: [:], encoding: JSONEncoding.default, headers: ["Authorization":"myToken"])
        .responseJSON {response in 

    guard response.result.error == nil else { 
       //HERE IS WHERE IS GOING IN WITH THE ERROR
    }
}

Any thoughts will be much appreciated or point me in the right direction :)

Answer 1

I got exact same error as yours in Cocoa with foundation class URLSession. After hours debugging the issue lies in the HTTP request body.

You should really try to dump the HTTP request/response body to see if there are some malformed fields. For example, Content-Length and Content-Type are right or missing? In my experience if these required(fundamental) headers are malformed, it may not work depending on your OS or other intermediate network accept(e.g. proxy, gateway, server, etc.)

My fault is misplacing function params in the method URLRequest.addValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type"), which ends up with a wrong Content-Type HTTP field.

However, it works in macOS 10.12 but not 12.11 so you should makes sure your HTTP Request body is not malformed.

Hope it helps.

---

Form your sample code, I guess the encoding: JSONEncoding.default is wrong. Since an HTTP GET method has NO body, a strict/not-robust network component would reject/not understand it.

What your goal is set the Accept: application/json in the request header, however it's not required if you're sure the response body type.