Problem with file submission through ajaxFormData

Good, I have a problem regarding the way you sent file values, how I use ajax in jquery and the jquery-formdata library, I get the error of TypeError: 'slice' called on an object that does not implement interface Blob. I think it's because all those values in the fields I store them as a JSON object, plus I use laravel to save the images, or at least that's supposed:

function FormInfo()
{
    var valor = $("#addUserForm").serialize();
    var json = {};

    var datos = valor.split("&");

    datos.forEach(function(element, index) {
        var info = element.split("=");
        json[""+info[0]] = info[1];
    });

    json["avatar"] = document.getElementById('plox').files[0];

    return json;
}

This is the code with which I get the values of the input and I pass them to a json as I add the value of the file.

$("#addUserForm").submit(function (event) {
    //Ocultando todos los mensajes de error
    $('.chip').hide();

    event.preventDefault();
    $.ajaxFormData({
        type: "post",
        dataType: "html",
        url: 'users/add',
        contentType: "multipart/form-data",
        data : FormInfo(),
        success: function (response) {
            $("#addUser").modal('close');
            $("#cont-users").addClass('formSubmitted');
            Materialize.toast('Registro ingresado', 3000, 'rounded');
        }

And this one here is the code by which I send the data, and this is the line of code of the user driver in laravel that gives me error:

$request->file('avatar')->store('public');

This is the form tag

<form method="POST" action="http://127.0.0.1:8000/users/add" accept-charset="UTF-8" id="addUserForm"><input name="_token" value="kl5DY0aNK0mUt3lR9pGnoeEX8GOlPhdLJkSSh0hd" type="hidden">