Alamofire invalid value around character 0

Question

Alamofire.request(.GET, "url").authenticate(user: "", password: "").responseJSON() {
    (request, response, json, error) in
    println(error)
    println(json)

}

This is my request with Alamofire, for a certain request it sometime works, but sometimes i get:

Optional(Error Domain=NSCocoaErrorDomain Code=3840 "The operation couldn’t be completed. (Cocoa error 3840.)" (Invalid value around character 0.) UserInfo=0x78e74b80 {NSDebugDescription=Invalid value around character 0.})

I've read that this can be due to invalid JSON, but the response is a static json string that i have validated in JSON validator as valid. It does contain å ä ö characters and some HTML.

Why am i getting this error sometimes?

Answer 1

I also faced same issue. I tried responseString instead of responseJSON and it worked. I guess this is a bug in Alamofire with using it with django.

Answer 2

I got same error while uploading image in multipart form in Alamofire as i was using

multipartFormData.appendBodyPart(data: image1Data, name: "file")

i fixed by replacing by

multipartFormData.appendBodyPart(data: image1Data, name: "file", fileName: "myImage.png", mimeType: "image/png")

Hope this help someone.

Answer 3

The same issue happened to me and it actually ended up being a server issue since the content type wasn't set.

Adding

.validate(contentType: ["application/json"])

To the request chain solved it for me

Alamofire.request(.GET, "url")
        .validate(contentType: ["application/json"])
        .authenticate(user: "", password: "")
        .responseJSON() { response in
            switch response.result {
            case .Success:
                print("It worked!")
                print(response.result.value)
            case .Failure(let error):
                print(error)
            }
        }

Answer 4

May this Help YOu

Alamofire.request(.GET, "YOUR_URL")
     .validate()
     .responseString { response in
         print("Success: \(response.result.isSuccess)")
         print("Response String: \(response.result.value)")
     }

Answer 5

I got the same error. But i found the solution for it.

NOTE 1: "It is not Alarmofire error", it's bcouse of server error.

NOTE 2: You don't need to change "responseJSON" to "responseString".

public func fetchDataFromServerUsingXWWWFormUrlencoded(parameter:NSDictionary, completionHandler: @escaping (_ result:NSDictionary) -> Void) -> Void {

        let headers = ["Content-Type": "application/x-www-form-urlencoded"]
        let completeURL = "http://the_complete_url_here"
        Alamofire.request(completeURL, method: .post, parameters: (parameter as! Parameters), encoding: URLEncoding.default, headers: headers).responseJSON { response in

            if let JSON = response.result.value {
                print("JSON: \(JSON)") // your JSONResponse result
                completionHandler(JSON as! NSDictionary)
            }
            else {
                print(response.result.error!)
            }
        }
    }

Answer 6

This is how I managed to resolve the Invalid 3840 Err.

The error log

 responseSerializationFailed(Alamofire.AFError.ResponseSerializationFailureReason.jsonSerializationFailed(Error Domain=NSCocoaErrorDomain Code=3840 "Invalid value around character 0." UserInfo={NSDebugDescription=Invalid value around character 0.}))

1. It was with Encoding Type used in the Request, The Encoding Type used should be acceptedin your Server-Side.

In-order to know the Encoding I had to run through all the Encoding Types:

default/ methodDependent/ queryString/ httpBody

    let headers: HTTPHeaders = [
        "Authorization": "Info XXX",
        "Accept": "application/json",
        "Content-Type" :"application/json"
    ]

    let parameters:Parameters = [
        "items": [
                "item1" : value,
                "item2": value,
                "item3" : value
        ]
    ]

    Alamofire.request("URL",method: .post, parameters: parameters,encoding:URLEncoding.queryString, headers: headers).responseJSON { response in
        debugPrint(response)
     }

2. It also depends upon the response we are recieving use the appropriate
   • responseString
   • responseJSON
   • responseData

If the response is not a JSON & just string in response use responseString

Example: in-case of login/ create token API :

"20dsoqs0287349y4ka85u6f24gmr6pah"

responseString

Answer 7

I solved using this as header:

let header = ["Content-Type": "application/json", "accept": "application/json"]

Answer 8

Maybe it is too late but I solved this problem in another way not mentioned here:

When you use .responseJSON(), you must set the response header with content-type = application/json, if not, it'll crash even if your body is a valid JSON. So, maybe your response header are empty or using another content-type.

Make sure your response header is set with content-type = application/json to .responseJSON() in Alamofire work properly.

Answer 9

Hey guys this is what I found to be my issue: I was calling Alamofire via a function to Authenticate Users: I used the function "Login User" With the parameters that would be called from the "body"(email: String, password: String) That would be passed

my errr was exactly:

optional(alamofire.aferror.responseserializationfailed(alamofire.aferror.responseserializationfailurereason.jsonserializationfailed(error domain=nscocoaerrordomain code=3840 "invalid value around character 0." userinfo={nsdebugdescription=invalid value around character 0

character 0 is the key here: meaning the the call for the "email" was not matching the parameters: See the code below

func loginUser(email: String, password: String, completed: @escaping downloadComplete) { let lowerCasedEmail = email.lowercased()

    let header = [
        "Content-Type" : "application/json; charset=utf-8"
    ]
    let body: [String: Any] = [
        "email": lowerCasedEmail,
        "password": password
    ]

    Alamofire.request(LOGIN_USER, method: .post, parameters: body, encoding: JSONEncoding.default, headers: header).responseJSON { (response) in
        if response.result.error == nil {

            if let data = response.result.value as? Dictionary<String, AnyObject> {
                if let email = data["user"] as? String {
                    self.userEmail = email
                    print(self.userEmail)
                }
                if let token = data["token"] as? String {
                    self.token_Key = token
                    print(self.token_Key)
                }

"email" in function parameters must match the let "email" when parsing then it will work..I no longer got the error...And character 0 was the "email" in the "body" parameter for the Alamofire request:

Hope this helps