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Fix "Uncaught TypeError: Cannot read property 'slice' of undefined" Error

I have created a new Telerk UI for ASP.NET Core R2 2018 SP1 Project and added a DropDownList Component into page.
When I use "Items" to add items manually everything is OK. but when I try to use DataSource to add Items using an Action remotely a console error is happened as "Uncaught TypeError: Cannot read property 'slice' of undefined".
JSON items is received and nothing is shown because of that error.
Please HELP

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    Milad Ashrafi shared this idea  ·   ·  Flag idea as inappropriate…  ·  Admin →

    3 comments

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      • Milad Ashrafi commented  ·   ·  Flag as inappropriate

        [HttpPost]
        public IActionResult Read()
        {
        var list = new[]
        {
        new TestModel
        {
        Text = "Text1",
        Value = 1
        },
        new TestModel
        {
        Text = "Text2",
        Value = 2
        }
        };
        return Json(list);
        }

      • Milad Ashrafi commented  ·   ·  Flag as inappropriate

        @(Html.Kendo().DropDownList().Name("DropDownElement")
        .DataTextField("Text")
        .DataValueField("Value")
        .DataSource(ds =>
        {
        ds.Ajax().Read(r =>
        {
        r.Action("Read", "Home");
        r.Type(HttpVerbs.Post);
        });
        }))

      • Milad Ashrafi commented  ·   ·  Flag as inappropriate

        kendo.all.js:7052 Uncaught TypeError: Cannot read property 'slice' of undefined
        at init.success (kendo.all.js:7052)
        at success (kendo.all.js:6979)
        at Object.i.success (kendo.all.js:5911)
        at i (jquery.min.js:2)
        at Object.fireWith [as resolveWith] (jquery.min.js:2)
        at y (jquery.min.js:4)
        at XMLHttpRequest.c (jquery.min.js:4)
        success @ kendo.all.js:7052
        success @ kendo.all.js:6979
        i.success @ kendo.all.js:5911
        i @ jquery.min.js:2
        fireWith @ jquery.min.js:2
        y @ jquery.min.js:4
        c @ jquery.min.js:4
        XMLHttpRequest.send (async)
        send @ jquery.min.js:4
        ajax @ jquery.min.js:4
        read @ kendo.all.js:5914
        read @ kendo.aspnetmvc.js:250
        (anonymous) @ kendo.all.js:6975
        _queueRequest @ kendo.all.js:7190
        read @ kendo.all.js:6968
        query @ kendo.all.js:7391
        _query @ kendo.all.js:7422
        fetch @ kendo.all.js:7418
        init @ kendo.all.js:35456
        (anonymous) @ kendo.all.js:2441
        each @ jquery.min.js:2
        each @ jquery.min.js:2
        e.fn.(anonymous function) @ kendo.all.js:2440
        (anonymous) @ (index):24
        i @ jquery.min.js:2
        fireWith @ jquery.min.js:2
        ready @ jquery.min.js:2
        K @ jquery.min.js:2

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