How to send post request from c# windows forms to a laravel api with files?

Question

I have a windows form that will send a post request to my simple laravel api.

Here's what I have done so far:

    private async void UploadScreenshot(string employee_id, string filepath)
    {

        string url = "http://127.0.0.1:8000/api/upload-screenshot";
     
        using (HttpClient client = new HttpClient())
        {
            var multiForm = new MultipartFormDataContent();


            Image ssimage = Image.FromFile(filepath);
            var byteimg = ImageToByteArray(ssimage);
            ByteArrayContent screenshotimg = new ByteArrayContent(byteimg);


            multiForm.Add(new ByteArrayContent(byteimg), "files");
            multiForm.Add(new StringContent(employee_id), "emp_number");


            var response = await client.PostAsync(url, multiForm);

            var responseString = await response.Content.ReadAsStringAsync();

            System.Windows.MessageBox.Show(responseString);
            //Console.WriteLine(responseString);

        }
    }

this code is working only for StringContent.but in my ByteArrayContent it returns null. Event using the MultipartFormDataContent. I tried every answer here in Stackoverflow since yesterday but no luck for me.

this is my Laravel API controller:

public function UploadScreenshot(Request $request){

    $emp_number = $request->emp_number; //this is working..
    $file = $request->files; //this is null

    if ($request->hasFile('screenshot')) {
        $file = request()->file('files');

        $fname = date('YmdHis');

        $ext = $request->files->extension();

        $filename = $fname . '.' . $ext;
       

        $file->storeAs('screenshots/', $filename, ['disk' => 'private']);

    }
}

Thanks.