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Hello everyone,

Here are the highlights of the new online resources we published this week from 10 Nov 2025 to 17 Nov 2025:

Article: https://www.telerik.com/aspnet-core-ui/documentation/ai-components-and-features
Summary: This article documents the AI Prompt and AI Chat components in Telerik UI for ASP.NET Core and shows you how to configure Tag/HTML Helpers and connect them to OpenAI or Azure OpenAI through ASP.NET Core endpoints. It covers setup, provider configuration, client/server APIs, streaming responses, attachments, context and message history, and content safety basics to help you implement AI features in your application.

Article: https://www.telerik.com/aspnet-core-ui/documentation/html-helpers/diagrams-and-maps/diagram/binding
Summary: You will bind the Telerik ASP.NET Core Diagram HTML Helper to your data so shapes and connections are generated from your schema. Configure DataSource and ConnectionsDataSource with model field mappings (Id, Text, X/Y for shape position; From/To for connections) and transport actions for server-side CRUD. The examples show remote binding, positioning, and handling data-bound events.

Article: https://www.telerik.com/aspnet-core-ui/documentation/html-helpers/diagrams-and-maps/diagram/razor-pages
Summary: This article shows how to use the ASP.NET Core Diagram HtmlHelper in Razor Pages: configure separate DataSources for shapes and connections with AJAX transport to page handlers (via Url.Page), map model fields (Id, From, To), and include the required Kendo UI scripts and styles. It provides .cshtml and PageModel code for Read, Create, Update, and Destroy operations and demonstrates adding anti-forgery tokens to the requests.

Feel free to check them out and share your thoughts!

The Telerik Team

Atanas
Telerik team
 updated question on 17 Nov 2025
5 answers
552 views
We need your feedback, because we are considering changes in the release approach for Telerik UI for ASP.NET Core. Please provide your feedback in the comments section below:


1. Is it hard to understand the version numbers of our releases? If yes, what makes them hard to understand them?

2. Would semantic versioning (SemVer) of our releases make it easier to understand our version numbers and what's behind them?

3. If we go with SemVer, we might need to start with version 3000.0.0 as we currently use 2022.x.x. Please share your thoughts about this approach and ideas for what number versioning would work best for you.

Chris
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Iron
 answered on 05 Feb 2024
1 answer
493 views

Hi!

The ListView is breaking my web application, and I cannot make head or tail of the reason:

An unhandled exception occurred while processing the request.

NotSupportedException: "ClientTemplateId or ClientTemplateHandler" cannot be null or empty.

Kendo.Mvc.UI.ListView<T>.VerifySettings()

 

Also, you demos for the ListView are broken and the browser tab crashed after a while.

I need an urgent fix, as this is affecting the live application.

Aleksandar
Telerik team
 answered on 17 Mar 2023
0 answers
557 views

In our UI for ASP.NET Core R3 2020 (2020.3.915) release, the Column menu message of unsticking a column is "null".

This bug will be resolved in our next official release.

In the meantime, as a workaround, manually set the Unstick Column menu message:

.ColumnMenu(c => c.Messages(m => m.Unstick("Unstick Column")))
Kendo UI
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 asked on 16 Sep 2020
0 answers
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I am converting a MVC table grid to a Telerik Grid. While looking at it, there are conditional columns. For example: 

 


@if (Model?.GroupDetail?.IsMec == false)
                                    {
                                        <th class="text-secondary" style="width: 140px;">Group Info</th>
                                    }

<th class="text-secondary">
                                        @if (Model?.GroupDetail?.IsMec == false)
                                        {
                                            <text>Office</text>
                                        }
                                        else
                                        {
                                            <text>Role</text>
                                        }
                                    </th>
How would I go about recreating something like this for the grid 
Charlston
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 asked on 19 Nov 2025
0 answers
8 views

I'm attempting to use the Kendo Upload control asynchronously to an MVC controller, which passes the file to a WebApi controller.  The file is uploaded successfully, however when it returns to the MVC view, it reports that the file failed to upload with the error below.  We are using Azure B2C for authentication:

"Access to XMLHttpRequest at 'https... b2clogin.com...' (redirected from 'https//localhost:7074/Files/UploadFile') from origin 'https://localhost:7074' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource."

Server response:

"Failed to load resource: net::ERR_FAILED"

The control is located in a partial view as part of a tab control on a CSHTML view.  Here is the code for the upload control:

<div class="row">
    <div class="col-md-8">
        @(Html.Kendo().Upload()
                .Name("uploadedFile")
            .Multiple(false)
            .Validation(v =>
            {
                v.AllowedExtensions(new string[] { ".csv" });
                v.MaxFileSize(3145728);
            })
            .Async(a => a
                .AutoUpload(false)
                .Save("UploadFile", "Files")
            )
            .Events(e =>
            {
    e.Upload("onFileUpload");
            })

         )
    </div>
    <div class="col-md-4">
    </div>

</div>

Here is the C# code for the MVC controller:

        [HttpPost]
        public async Task<ActionResult> UploadFile(IFormFile uploadedFile, string month, string year)
        {
            if (uploadedFile == null || uploadedFile.Length == 0)
                return BadRequest("No file uploaded.");

            var reportingPeriod = month + year;

            using (var content = new MultipartFormDataContent())
            {
                if (uploadedFile.Length > 0)
                {
                    var streamContent = new StreamContent(uploadedFile.OpenReadStream());
                    streamContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(uploadedFile.ContentType);
                    content.Add(streamContent, "file", uploadedFile.FileName);
                }

                using (var response = await _client.HttpClient.PostAsync("/api/Files/loadbackdatedmonthlytrueupfile/" + reportingPeriod, content))
                {
                    if (response.IsSuccessStatusCode)
                    {
                        // Kendo expects an empty string for success
                        return Content("");
                    }
                    else
                    {
                        return StatusCode((int)response.StatusCode, await response.Content.ReadAsStringAsync());
                    }

                }

            }
        }

 

Here is the code for the WebApi controller:

[HttpPost("loadbackdatedmonthlytrueupfile/{reportingPeriod}")]
public async Task<IActionResult> LoadBackdatedMonthlyTrueUpFile([FromForm] IFormFile file, string reportingPeriod)

{

     //other logic here

     return Ok(new { file.FileName, file.Length });

}

This is the info I received from Copilot:

This error is caused by trying to call the Azure AD B2C /authorize endpoint using an XMLHttpRequest (AJAX/fetch) from your frontend (https://localhost:7074). Azure AD B2C does not support CORS for this endpoint, so the browser blocks the request.
Root cause:
• The /authorize endpoint is designed for browser redirects, not AJAX/fetch/XHR.
• No CORS headers will ever be present on this endpoint, so preflight requests will always fail.
How to fix:
• Never use AJAX/fetch/XHR to call the /authorize endpoint.
• Always use a full-page redirect for authentication.
For example, set window.location.href to the login URL, or let the [Authorize] attribute and OIDC middleware handle it for you.

How can I configure this upload control to return to the view without the error (attaching screenshot)?

Wendy
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 asked on 17 Nov 2025
1 answer
30 views
Can we show actual image as a thumbnail in the content pane of the filemanager ?
I have read the documentation but didn't find any suitable reference. 

thats what i meant

Ivaylo
Telerik team
 answered on 30 Oct 2025
1 answer
15 views

when am used DropDownTree control i am used below sample format

@(Html.Kendo().DropDownTree()
       .Name("ID")
       .Label(label =>
       {
           label.Content("Select an ID...");
       })
       .DataTextField("Name")
       .DataValueField("id").Value(12)
       .HtmlAttributes(new { style = "width: 100%" })
       .Filter(FilterType.Contains)
       //.LoadOnDemand(true)
       .DataSource(dataSource => dataSource.ServerFiltering(true).Read(read => read.Action("GetLocationListForDDTree", "Home") ) )
   )

when enable loadondemand it works filter but value not show selected . if am command the loadondemand its show the selected value but filter not working . i need both options kindly advice this 

 

Eyup
Telerik team
 answered on 23 Oct 2025
1 answer
15 views

I am trying to put an "action" menu on the toolbar of my grid.  I have used a dropdownlist as is shown on your examples.  The issue that I have with this is that action menus have a placeholder because all of the menu items have equal importance so no one menu item is the default.  So I have rigged up menu like events with my javascript but it is still not ideal since the "placeholder" is a selectable list item.  So then I had the brilliant idea of using telerik's menu within my custom client template.  Easy peasy.  Right? No, the dropdown or the .k-animation-container .k-animation-container-shown's z-order is 10002 and no matter how hard I try I can't get it to change and the dropdown is hidden by the grid header.

I was left to wonder if it is because it is limited to the confines of the toolbar.  I am open to suggestions.  I would hate to have to go back to the clunky dropdownlist option.  Here's my code:

<style>
    .k-animation-container, .k-animation-container-shown{
        z-index: 30000 !important;
    }
</style>
@(
Html.Kendo().Grid<CommunityAssociationMasterModel>()
    .Name("CommunityAssociationMasterList")
    .Columns(columns =>
    {
        columns.Bound(p => p.DistrictCode).Title("District").Width(70);
        columns.Bound(p => p.IndexNumber).Title("Index").Width(100);
        columns.Bound(p => p.CreditName).Title("Credit");
        columns.Command(command => { command.Destroy(); }).Width(210);
    })
    .ToolBar(toolbar => { 
        toolbar.Create().Text("Add Credit Account"); 
        toolbar.Excel();
        toolbar.Spacer();
        toolbar.Custom().ClientTemplate(
            Html.Kendo().Template()
            .AddComponent(c => c
                .Menu()
                .Name("actionmenu")
                .Items(items =>
                {
                    items.Add().Text("Master List Action")
                    .Items(children =>
                    {
                        children.Add().Text("Import");
                        children.Add().Separator(true);
                        children.Add().Text("Delete");
                    });
                })                           
                .Events(e => e.Select("actionSelected"))
                .HtmlAttributes(new { style = "width: 200px;" })
            )
        );
Eyup
Telerik team
 answered on 21 Oct 2025
1 answer
11 views
DatePickerFor does not work with any versions newer than 2025-2-702. As a result, we cannot upgrade our telerik version to newer versions. Non model bound DatePicker works. When using DatePickerFor, it completely stops rendering the date picker and subsequent html.
Ivaylo
Telerik team
 answered on 17 Oct 2025
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