alamofire.error Code=-6006 "JSON could not be serialized

This is not Alamofire or swift error, The response returned by the server is not in the JSON format. you can print out response data and check what is wrong in this.

try this code to print out our server data to easily identifying to error and resolve this.

Alamofire.request("Your url").responseJSON(completionHandler: { (response) in    switch response.result {    case .success(let value):        break    case .failure(let error):        print("\n\n===========Error===========")        print("Error Code: \(error._code)")        print("Error Messsage: \(error.localizedDescription)")        if let data = response.data, let str = String(data: data, encoding: String.Encoding.utf8){            print("Server Error: " + str)        }        debugPrint(error as Any)        print("===========================\n\n")    }})

The response returned by the server is not in the JSON format. You can use the tool to test the request first.

Print out of the error code is not a HTTP error code, because of the failure to resolve JSON

You need to check the mimeType it will be "text/plain" instead of "application/json". That's why JSONSerialization class not able to parse the data.