I cannot save in database my HTML signature canvas value

Question

I created a signature pad with HTML. I assigned canvas value to a variable by id, then I converted the assigned value to URL with the toDataURL command. I want to send this URL to the controller with AJAX and save it in database, but I get a 404 error because the data URL is too long. I'll be happy if you can help me. Here is my code.

HTML:

@using RasyoMed.WEBUI.Controllers.Classes
<div class="col-md-12">
    <label class="baslik">İmza</label>
</div>
<div class="col-md-12">
    <canvas id="sig-canvas-@Model" class="sig-canvas test" download="new-image-name.jpg" width="620" height="160"></canvas>
</div>
<div class="col-md-12">
    <button type="button" id="sig-clearBtn-@Model" class="btn btn-warning">İmza Temizle</button>
    <button type="button" id="sig-saveBtn-@Model" class="btn btn-success">İmza Kaydet</button>
</div>

JavaScript:

        saveBtn.addEventListener("click", function (e) {
            var dataURL = canvas.toDataURL();
            dataURL = dataURL.replace('data:image/png;base64,', '');
            imzaKaydet(dataURL);
        }, false);

 function imzaKaydet(dataURL) {
            debugger;
            $.ajax({
                url: '/HemsireFormlari/ImzaKaydet',
                type: 'POST',
                dataType: 'json',
                data: {
                    dataURL: dataURL
                },
                type:'GET',
                contentType: "application/json;charset=utf-8",
                dataType: "json",
                success: function (result) {
                    if (result == "Başarılı") {
                        Swal.fire({
                            type: 'success',
                            title: "İmzanız kaydedilmiştir.",
                            showConfirmButton: false,
                            timer: 1500
                        })
                    }
                },
                error: function (xhr) {
                    //Ajax request failed.
                    var errorMessage = xhr.status + ': ' + xhr.statusText
                    Swal.fire({ type: 'error', title: 'Hata !', text: 'Error - ' + errorMessage })
                }
            });
        }

Controller:

 public JsonResult ImzaKaydet(string dataURL)
        {
            int KullaniciId = Convert.ToInt32(Session["KullaniciId"]);
            KullaniciImza kImza = new KullaniciImza();
            RepositoryBase<KullaniciImza> rbhastadosyaFormu = new RepositoryBase<KullaniciImza>(new YBDBEntities());
            kImza = db.KullaniciImza.Where(x => x.KullaniciId == KullaniciId).FirstOrDefault();
            if(kImza == null)
            {
                kImza.KullaniciId = KullaniciId;
                kImza.ImzaPath = dataURL;
               rbhastadosyaFormu.Ekle(kImza);
            }
            else
            {
                kImza.ImzaPath = dataURL;

                rbhastadosyaFormu.Guncelle(kImza);
            }
          
            return Json("Başarılı", JsonRequestBehavior.AllowGet);
        }