Dhtmlx vault upload file method not allow


Hi all.

I made a page as an example https://docs.dhtmlx.com/vault/how_to_start.html

But when I try to upload a file to a folder, I get an error image

My code

    <title>Server data</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link href="https://fonts.googleapis.com/css?family=Roboto:400,500" rel="stylesheet">
    <script type="text/javascript" src="../../codebase/vault.js?v=3.0.0"></script>
    <link rel="stylesheet" type="text/css" href="../../codebase/vault.css?v=3.0.0">
    <script type="text/javascript" src="../common/js/index.js?v=3.0.0"></script>
    @*<link rel="stylesheet" type="text/css" href="../common/dhx_samples.css?v=3.0.0">*@
    <div id="vault_container"></div>



     var myVault = new dhx.Vault("vault_container", {
            target: "/vault/backend/upload"



I apologize for the delay.
Unfortunately the problem cannot be reconstructed locally.
COuld you pleas,e provuide a complete demo including your server-side code, s othe porblem could be reconstructed locally.