I'm getting a 406 response error when I try to make a https request (Note: no error when i use just http)

Question

I'm using the cordova file-transfer plugin in order for users to upload pictures within my app.

My code works perfectly when making a normal http request to the php page on my server. I would like to make a secure request so am trying to use https however I am getting a 406 error (see screenshot for error details)

All other ajax requests I am making within the app are working successfully using https.

I am currently not sending any headers when making the request however there is an option to do this using the file-transfer plugin.

I have looked into how I can solve this error (for example this question here) however am still uncertain as to what I need to do in my case. I was wondering can you help determine what headers I need?

Here is my code:

Javascript

function uploadProfilePic(){
    var token = localStorage.getItem("usertoken");      
    var defs = [];
    var def = $.Deferred();
    function win(r) {   

        if($.trim(r.response) === "0") {
            alert("Sorry! We have encountered an error");
            def.resolve(0);
        }else{

            def.resolve(1);     
        }
    }       
    function fail(error) {

        //upload of pic failed.
        alert("Sorry! We have encountered an error: " + JSON.stringify(error));
        def.resolve(0);
    }
    var uri = encodeURI("https://www.example.com/update_profile_pic.php");

    var options = new FileUploadOptions();
    options.fileKey="profile_pic_image_file";
    options.mimeType="image/jpeg";

    var params = new Object();
    params.usertoken = token; 
    params.app_root_url = app_root_url;

    //not sure what headers to add here.
    //var headers={'headerParam':'headerValue'};
    //options.headers = headers;

    options.params = params;


    var ft = new FileTransfer();
    ft.onprogress = function(progressEvent){
        if(progressEvent.lengthComputable){
                loadingStatus.setPercentage(progressEvent.loaded / progressEvent.total);
            }else{
                loadingStatus.increment();
            }
    };

    ft.upload($ESAPI.encoder().encodeForURL(profileImage), uri, win, fail, options);
    defs.push(def.promise());

    $.when.apply($, defs).then(function() { 
        //pic uploaded fine

    }); 
}

PHP (upload_profile_pic.php)

header("Access-Control-Allow-Origin: *");   

if(isset($_FILES['profile_pic_image_file'])){
    $data['profile_image_is_set'] = true;


    //do stuff with profile image here

    echo json_encode($data);
}else{
    $data['profile_image_is_set'] = false;
        //image not set 
    echo json_encode($data);
}