Unable to load the service index for source https://nuget.telerik.com/v3/index.json. 
Response status code does not indicate success: 401 (Unauthorized).
 
In the "tools -> nuget package manager -> package manager settings -> nuget package manager -> configuration files", I see several nuget.config files.
The first nuget.config in the list is in located in the solution folder.
The second nuget.config in located in the "users\myname\AppData\roaming\nuget\" folder
The second nuget.config contains my nuget.telerik UID and PW. The first nuget.config does not have that info. Not sure if this matters or if I can switch the priority.
Also, I tried downloading my "telerik-license.txt" and placed it in my solution folder. Did not help.
Online it says to add source "https://nuget.telerik.com/v3/index.json" and use telerik UI and PW. Unsure where to do this.
I also removed then added the "Sources" through the VS2026 UI "nuget package manager -> sources", shown here. But I was never asked for a UID and PW as the articles online say would happen.
nuget.org	https://api.nuget.org/v3/index.json
TelerikOnlineFeed	https://nuget.telerik.com/v3/index.json
 
Also, when I open this solution in VS2026, a dialog appears asking to update "Telerik UI for ASP.NET Core version update". 
"Version Update" -> "Please, log in to download the latest version of Telerik UI for ASP.Net Core"
When I click the button, a web page appears saying I was successfully logged into telerik. When I return to VS2026, there is an error:
"Authentication did not succeed. Please try again"
 
How can I resolve this?
 

[
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 1",
    "color": "red",
    "dateInfo": "2026-01-01T00:00:00",
    "consumption": "44.35"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 1",
    "color": "red",
    "dateInfo": "2026-01-02T00:00:00",
    "consumption": "44.38"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 1",
    "color": "red",
    "dateInfo": "2026-01-03T00:00:00",
    "consumption": "44.38"
  },
   {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 2",
    "color": "blue",
    "dateInfo": "2026-01-01T00:00:00",
    "consumption": "291.59"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 2",
    "color": "blue",
    "dateInfo": "2026-01-02T00:00:00",
    "consumption": "293.00"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 2",
    "color": "blue",
    "dateInfo": "2026-01-03T00:00:00",
    "consumption": "289.21"
  },
 {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 3",
    "color": "yellow",
    "dateInfo": "2026-01-01T00:00:00",
    "consumption": "228.62"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 3",
    "color": "yellow",
    "dateInfo": "2026-01-02T00:00:00",
    "consumption": "577.15"
  },
  {
    "powerDeviceName": "Datarack",
    "powerDeviceUnitName": "Datarack Fas 3",
    "color": "yellow",
    "dateInfo": "2026-01-03T00:00:00",
    "consumption": "295.35"
  }
]

jQuery.Deferred exception: mI is not a function TypeError: mI is not a function
  at DV.loadDocument (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4666164)
    at DV.loadFile (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4666007)
    at new DV (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4660492)
    at init._loadPdfJSDocument (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4725966)
    at new init (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:4710755)
    at HTMLDivElement.<anonymous> (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:66968)
    at ce.each (http://localhost:56126/js/jquery-3.7.0.min.js:2:3129)
    at ce.fn.init.each (http://localhost:56126/js/jquery-3.7.0.min.js:2:1594)
    at e.fn.<computed> [as kendoPDFViewer] (http://localhost:56126/lib/kendo-ui/js/kendo.all.min.js:9:66944)
    at HTMLDocument.<anonymous> (http://localhost:56126/MyFolder/MyPage?ticketid=11:703:100) undefined

<div class="container">
@(Html.Kendo().Grid<Kendo.Mvc.Examples.Models.EmployeeViewModel>()
    .Name("Grid")
    .Columns(columns => {
        columns.Command(command => command.Custom("Close").Click("showDetails").Visible("colVisible"));
        columns.Bound(e => e.Title);
        columns.Group(group => group
            .Title("Name")
            .Columns(name => {
                name.Bound(e => e.FirstName).Width(80);
                name.Bound(e => e.LastName).Width(80);
            })
        );
        columns.Bound(e => e.FirstName).Width(80);
        columns.Bound(e => e.LastName).Width(80);
        columns.Bound(e => e.Title).Width(250);
        columns.Bound(e => e.FirstName).Width(80);
        columns.Bound(e => e.LastName).Width(80);
        columns.Bound(e => e.Title).Width(250);

    })
    .Size(ComponentSize.Small)
    .Scrollable()
    .Sortable()
    .Resizable(resize => resize.Columns(true))
    .DataSource(dataSource => dataSource
        .Ajax()
        .Read(read => read.Action("CustomCommand_Read", "Grid"))
     )
)
</div>
@(Html.Kendo().Window().Name("Details")
    .Title("Customer Details")
    .Visible(false)
    .Modal(true)
    .Draggable(true)
    .Width(300)
)

 <script type="text/x-kendo-template" id="template">
    <div id="details-container">
        <h2>#= FirstName # #= LastName #</h2>
        <em>#= Title #</em>
        <dl>
            <dt>City: #= City #</dt>
            <dt>Address: #= Address #</dt>
        </dl>
    </div>
</script>

   function showDetails(e) {
        e.preventDefault();

        var detailsTemplate = kendo.template($("#template").html());
        var dataItem = this.dataItem($(e.currentTarget).closest("tr"));
        var wnd = $("#Details").data("kendoWindow");

        wnd.content(detailsTemplate(dataItem));
        wnd.center().open();
    }

    function colVisible(dataItem) {
        var visible = dataItem.LastName == "Fuller";
        return !visible;
    }