In Development
Last Updated: 21 Oct 2026 14:27 by ADMIN
Scheduled for 2026 (Nov)
Created by: Walter
Comments: 0
Category: UI for Blazor
Type: Bug Report
0

Bug report

Reproduction of the problem

(bug report only)
Environment

  • Version 15.1.0
  • Blazor Server, .NET 10
  • Chromium (Chrome and Playwright headless)

TabStrip Tab is never destroyed
Components/TabStrip/Tab.razor.cs registers each tab with initTabStripTab in OnAfterRenderAsync. Its Dispose() only releases the DotNetObjectReference; it never calls InvokeDisposeAsync(). The JS Tab.destroy() method is therefore never called, and TabStrip.destroy() does not destroy its child tabs. Every tab stays in window.TelerikBlazor._instances with its detached <li class="k-tabstrip-item">, which again keeps the disposed page reachable.

  1. Create two routable pages. PageA has TabStrip with 3 tabs. PageB is empty.
  2. Open PageA, then navigate to PageB with the in-app router (no full reload).
  3. Run this in the browser console:
Object.entries(TelerikBlazor._instances)
     .filter(([k, i]) => i && i.element && !i.element.isConnected)
     .map(([k, i]) => k + ' / ' + i.constructor.name)

Sample project attached.

TelerikBlazorApp1.zip

Current behavior

(optional)
One entry per TabStrip tab is returned, all pointing at detached elements. Each pageA -> pageB round trip adds more, and the detached DOM is never released.

Expected/desired behavior

An empty array is returned. PageA's components were disposed, so their JS instances should have been destroyed.

Workaround

After each navigation, we destroy and remove any registered instance whose element is no longer in the page:

const instances = window.TelerikBlazor && window.TelerikBlazor._instances;
   for (const key of Object.keys(instances || {})) {
       const i = instances[key];
       if (i && i.element && !i.element.isConnected) {
           try { i.destroy && i.destroy(); } catch (e) { }
           delete instances[key];
       }
   }

Suggested Fix

  1. In Tab.Dispose(), call InvokeDisposeAsync() before base.Dispose(), as TelerikTabStrip.Dispose() does.

Environment

  • Kendo/Telerik version:
  • Browser: [Chrome XX , Firefox]
Unplanned
Last Updated: 21 Oct 2026 13:59 by ADMIN
Scheduled for 2026 (Nov)
Created by: Walter
Comments: 0
Category: UI for Blazor
Type: Bug Report
0

Bug report

Reproduction of the problem

Environment

  • Version 15.1.0
  • Blazor Server, .NET 10
  • Chromium (Chrome and Playwright headless)

Grid ColumnDraggable is never destroyed
In Components/Common/Grid/Rows/TableHeaderRow.cs, Dispose() calls base.Dispose() first, which sets IsDisposed = true. It then calls DestroyColumnDraggable(), which uses InvokeAsync<object>. That method returns early when IsDisposed is true (BaseComponent.InvokeAsync<T>), so destroyColumnDraggable is never sent to the browser. DestroyColumnReorderable() and DestroyColumnResizable() work because they use InvokeVoidAsync, which has no such check.

As a result, every grid with Reorderable="true" or Groupable="true" leaves "<dataId>-telerik-ColumnDraggable" in window.TelerikBlazor._instances. Its draggable.element (the grid's .k-grid-header) keeps the whole disposed page reachable, so the page is never garbage collected.

  1. Create two routable pages. Page A has a TelerikGrid with Reorderable="true" and a TelerikTabStrip with a few tabs. Page B is empty.
  2. Open Page A, then navigate to Page B with the in-app router (no full reload).
  3. Run this in the browser console:
Object.entries(TelerikBlazor._instances)
     .filter(([k, i]) => i && i.element && !i.element.isConnected)
     .map(([k, i]) => k + ' / ' + i.constructor.name)

Sample project attached.

TelerikBlazorApp1.zip

Current behavior

(optional)
one "...-telerik-ColumnDraggable" entry per reorderable or groupable grid, all pointing at detached elements. Each pageA -> pageB round trip adds more, and the detached DOM is never released.

Expected/desired behavior

An empty array is returned. Page A's components were disposed, so their JS instances should have been destroyed.

Workaround

After each navigation, we destroy and remove any registered instance whose element is no longer in the page:

   const instances = window.TelerikBlazor && window.TelerikBlazor._instances;
   for (const key of Object.keys(instances || {})) {
       const i = instances[key];
       if (i && i.element && !i.element.isConnected) {
           try { i.destroy && i.destroy(); } catch (e) { }
           delete instances[key];
       }
   }

Suggested Fix

  1. In TableHeaderRow.DestroyColumnDraggable(), use InvokeVoidAsync, as DestroyColumnReorderable() does. Or call the destroy methods before base.Dispose().

Environment

  • Kendo/Telerik version:
  • Browser: [Chrome XX, Firefox]
Completed
Last Updated: 21 Oct 2026 10:05 by ADMIN
Release 2026 (Nov)
Created by: Kees
Comments: 5
Category: FileManager
Type: Feature Request
51

The ability to choose which options to appear in the ContextMenu.

=====

TELERIK EDIT: In the meantime, here is how to hide context menu items with CSS:

    /* Hide the Rename item in the FileManager context menu */
    .k-context-menu:has(.k-svg-i-download) .k-menu-item:nth-of-type(1) {
        display: none;
    }

    /* Hide the Delete item in the FileManager context menu */
    .k-context-menu:has(.k-svg-i-download) .k-menu-item:nth-of-type(3) {
        display: none;
    }

Here is a complete example: https://blazorrepl.telerik.com/cpPkuBEq408A36p010

 

Planned
Last Updated: 20 Oct 2026 08:26 by ADMIN
Scheduled for 2026 (Nov)

Example:

<PageTitle>Home</PageTitle>

<div>
    <TelerikTextBox Width="20rem" Placeholder="Pallet" DebounceDelay="1000" @bind-Value="@_textInput" OnChange="@(async (input) => await OnInputChanged(input))" />
</div>
<p>@_textInput</p>


@code {
    private string? _textInput;

    private async Task OnInputChanged(object input)
    {
        Console.WriteLine($"Immediate: function parameter: {input}, bound variable: {_textInput}");
        await Task.Delay(1000);
        Console.WriteLine($"Delayed: function parameter: {input}, bound variable: {_textInput}");
        //Make the OnChange event receive the immediate value when the DebounceDelay is set
    }
}

The DebounceDelay is set to 1 second to highlight the behavior, although we have observed it with delays less than 100 milliseconds when the input is from a barcode scanner and the Enter is part of the scan. Start the sample, type "123" in the input, and hit enter within 1 second.

The output in the console is:
Immediate: function parameter: , bound variable:
Delayed: function parameter: , bound variable: 123

Planned
Last Updated: 20 Oct 2026 08:26 by ADMIN
Scheduled for 2026 (Nov)
Created by: Santiago
Comments: 0
Category: ComboBox
Type: Bug Report
4

(Also applies to AutoComplete, DropDownList, MultiSelect, MultiColumnComboBox).

When using Height="auto" in the popup settings and filtering with a dropdown above the component, the dropdown detaches from the main component.

<ComboBoxPopupSettings Height="auto"></ComboBoxPopupSettings>

https://blazorrepl.telerik.com/cKkSQGFO50ovCpr829

A possible workaround is to use a MaxHeight that is less than half the browser viewport.

<ComboBoxPopupSettings Height="auto" MaxHeight="45vh"></ComboBoxPopupSettings>

In Development
Last Updated: 20 Oct 2026 08:26 by ADMIN
Scheduled for 2026 (Nov)

Bug report

Reproduction of the problem

(bug report only)
The label of the filter menu icon displays: “column filter menu settings”. In version 12.0.0 it included the name of the column field.

1. Run this example: https://blazorrepl.telerik.com/cKFaOPvO56rcaHqx16
2. Hover a filter icon in the Grid’s header with the mouse cursor.

Current behavior

(optional)
The label “column filter menu settings” appears.

Expected/desired behavior

The label text includes the column name, e.g., “Price column filter menu settings”.

Workaround:

https://blazorrepl.telerik.com/cUPYaPlO55EJNiKJ24

Environment

  • Kendo/Telerik version: 15.0.1
  • Browser: [all]
Declined
Last Updated: 20 Oct 2026 07:52 by ADMIN

I am trying to look at the times 7pm - midnight.  But if I set the end time to midnight, I get an error that the end time has to be greater than the start time.  How do I set the timeline to show 7pm - midnight or 8pm - 2am?

I tried including the next date in the EndTime but the Scheduler does not take the date into consideration, it checks only the time portion.

Completed
Last Updated: 20 Oct 2026 07:28 by ADMIN
Release 2025 Q3 (Aug)
Created by: Tobias
Comments: 7
Category: Grid
Type: Feature Request
38

Hello,

Please consider a Grid feature that changes the component layout on mobile devices or narrow screens. The idea is to switch the column layout to a card layout or anything similar to this example: https://css-tricks.com/responsive-data-tables/

It is possible to implement a similar behavior with the Telerik Blazor Grid and MediaQuery components, but it requires reusing the column titles in the CSS code: https://blazorrepl.telerik.com/GnYPmHFR176Jg5Yg02

===

Telerik Blazor team: Everyone who is interested in this feature, please vote for it to help us prioritize. Also, share your opinion about which Grid features you strictly need in the "mobile" layout and which ones you are ready to sacrifice. Some features don't make sense in a card / listview layout anyway, but still, the mobile-friendly Grid may require completely different HTML markup and UX, so some features may need to be completely revamped.

Planned
Last Updated: 19 Oct 2026 12:19 by ADMIN
Scheduled for 2026 (Nov)

Title: WCAG 1.3.1: Ensures elements with an ARIA role that require child roles contain them (#\39 374a450-079d-4586-b823-d6bc7723505f)
Tags: Accessibility, WCAG 1.3.1, aria-required-children

Issue: Ensures elements with an ARIA role that require child roles contain them (aria-required-children - https://accessibilityinsights.io/info-examples/web/aria-required-children)

Target application: Hermes Home - https://localhost/TrafficLoss

Element path: #\39 374a450-079d-4586-b823-d6bc7723505f

Snippet: <div class="k-grid-aria-root" id="9374a450-079d-4586-b823-d6bc7723505f" role="grid" aria-label="Data table">

How to fix: 
Fix any of the following:
  Element has children which are not allowed (see related nodes)
  Element has no aria-busy="true" attribute

Environment: Microsoft Edge version 111.0.1661.41

====

This accessibility issue was found using Accessibility Insights for Web 2.37.3 (axe-core 4.6.3), a tool that helps find and fix accessibility issues. Get more information & download this tool at http://aka.ms/AccessibilityInsights.

 

============================  code =============================

                           <TelerikGrid Data="@ViewModel.RDLInformation" TItem="TLSummary"
                                                        Pageable="true" 
                                                        Sortable="true" 
                                                        Groupable="false"
                                                        FilterMode="Telerik.Blazor.GridFilterMode.FilterRow"
                                                        Resizable="true" 
                                                        Reorderable="true"
                                                        Height = "100%">

....

                            </TelerikGrid>

Planned
Last Updated: 19 Oct 2026 10:37 by ADMIN
Scheduled for 2026 (Nov)
Our "Level Access" accessibility scanning tool revealed that the RadioGroup component uses the aria-checked=true with input[type=radio] which could cause accessibility issues if conflicting.
Unplanned
Last Updated: 19 Oct 2026 09:52 by Wes
Created by: Wes
Comments: 0
Category: PDFViewer
Type: Bug Report
1

The PDF Viewer may render parts of the contents as blank (empty space) and only form elements like checkboxes remain visible.

Test PDF file in ticket 1716925

Unplanned
Last Updated: 16 Oct 2026 15:05 by ADMIN

My users use Tab to focus the masked textbox and when they start typing (its content was highlighted because of getting focus with Tab), that typing action does not put the range (caret) in the correct place - it remains at position 0 rather than going to position 1.

For example, in the below phone mask they type "9" and then "0" and I would expect to get "90" but I get "0".

---

ADMIN EDIT

A workaround is to collapse the range when the input gets focus:

@inject IJSRuntime JsInterop

<input />
<span @onfocusin="@CollapseInputSelection" @ref="@ParentElem">
    <TelerikMaskedTextBox Mask="+1 (000) 000-0000"
                          IncludeLiterals="true"
                          @bind-Value="@CellPhoneNumber"
                          Class="form-control" />
</span>

@* move this script to an actual script file instead of using this hack *@
<script suppress-error="BL9992">
    function collapseInputSelection(root) {
        setTimeout(function () {
            var input = root.querySelector("input");
            if (input) {
                input.setSelectionRange(0, 0);
            }
        }, 20);
    }
</script>

@code{
    string CellPhoneNumber { get; set; }

    ElementReference ParentElem { get; set; }
    async Task CollapseInputSelection()
    {
        await JsInterop.InvokeVoidAsync("collapseInputSelection", ParentElem);
    }
}

---

Unplanned
Last Updated: 16 Oct 2026 14:50 by ADMIN
Created by: const
Comments: 2
Category: DateTimePicker
Type: Bug Report
2

I want the user to only be able to select times between, for example, 11AM and 1PM. Setting Min and Max does not limit that, I can select any time:

Selected time: @selectedTime
<br />

<TelerikDateTimePicker Min="@Min" Max="@Max" @bind-Value="@selectedTime"
                       Format="dd MMM yyyy HH:mm" Width="250px"></TelerikDateTimePicker>

@code {
    private DateTime? selectedTime = DateTime.Now;
    public DateTime Min = new DateTime(2020, 6, 11, 10, 15, 0);
    public DateTime Max = new DateTime(2020, 6, 13, 12, 30, 45);
}
Unplanned
Last Updated: 16 Oct 2026 14:36 by ADMIN
I have a TreeList, bound to an ObservableCollection data source. When I try to add new children the component stays in Create mode even after I click on the Update button.
Unplanned
Last Updated: 16 Oct 2026 14:29 by ADMIN
Created by: chris
Comments: 2
Category: RadioGroup
Type: Bug Report
1

A RadioGroup inside a Grid EditorTemplate will fire OnBlur when the user clicks on it. This will close the edit cell and (usually) not apply the new value.

Here is a test page: https://blazorrepl.telerik.com/wvbmkMvd48rpMN4547

Unplanned
Last Updated: 16 Oct 2026 14:01 by ADMIN
Cannot remove the last series of a dynamically created chart
Unplanned
Last Updated: 16 Oct 2026 13:09 by ADMIN

The code below compiles and doesn't give any browser errors when run, but when you collapse a row, all data is collapsed and you can't expand it again.

If you change the line that generates the data to use a List instead of IEnumerable it will work as expected.

REPRODUCIBLE

<TelerikTreeList Data=Data
                 IdField="@nameof(Record.Id)"
                 ParentIdField="@nameof(Record.ParentId)"
                 Height="100%">
    <TreeListColumns>
        <TreeListCheckboxColumn CheckBoxOnlySelection="true" />
        <TreeListColumn Field="@nameof(Record.Text)" Title="" Expandable="true" />
        <TreeListColumn Field="@nameof(Record.Id)" Title="ID" />
        <TreeListColumn Field="@nameof(Record.ParentId)" Title="PARENT" />
    </TreeListColumns>
</TelerikTreeList>
@code {
    protected IEnumerable<Record> Data = new List<Record>();

    protected override void OnInitialized()
    {
        Data = Enumerable.Range(1, 10).Select(i => new Record(i));
    }

    public class Record
    {
        public Record(int i)
        {
            Id = i;
            if (i % 5 == 1)
                ParentId = null;
            else
                ParentId = (i - ((i - 1) % 5));
            Text = "Item " + i;
        }
        public long Id { get; set; }
        public long? ParentId { get; set; }
        public string Text { get; set; }
    }
} 

WORKAROUND

<TelerikTreeList Data=Data
                 IdField="@nameof(Record.Id)"
                 ParentIdField="@nameof(Record.ParentId)"
                 Height="100%">
    <TreeListColumns>
        <TreeListCheckboxColumn CheckBoxOnlySelection="true" />
        <TreeListColumn Field="@nameof(Record.Text)" Title="" Expandable="true" />
        <TreeListColumn Field="@nameof(Record.Id)" Title="ID" />
        <TreeListColumn Field="@nameof(Record.ParentId)" Title="PARENT" />
    </TreeListColumns>
</TelerikTreeList>
@code {
    protected List<Record> Data = new List<Record>();

    protected override void OnInitialized()
    {
        Data = Enumerable.Range(1, 10).Select(i => new Record(i)).ToList();
    }

    public class Record
    {
        public Record(int i)
        {
            Id = i;
            if (i % 5 == 1)
                ParentId = null;
            else
                ParentId = (i - ((i - 1) % 5));
            Text = "Item " + i;
        }
        public long Id { get; set; }
        public long? ParentId { get; set; }
        public string Text { get; set; }
    }
} 

 

Unplanned
Last Updated: 16 Oct 2026 08:28 by ADMIN

Entering dates in the Blazor spreadsheet act weird if you enter a 2 digit year. It seems to subtract a day when you remove focus from the cell.

Start by entering a date like 2/2/25:

Then hit enter or otherwise remove focus from the cell and this is what it changes it to. Notice it subtracts a day:

Then put focus back on the cell:

Now look at the editor at the top:

I note that when you enter a two digit year in Excel it defaults the century to 20 when you enter a year less than 30. It defaults a century of 19 when you enter a year >= 30. It appears that with the Telerik Blazor spreadsheet it always defaults the century to 19. You can make arguments on either side of that but the real issue here is that it subtracts a day when you enter a two digit year. It doesn't do that when you enter a 4 digit year.

The related thing that becomes an issue is when you export the spreadsheet to a byte array and evaluate the cell RawValue. When you enter a 4 digit year, you get a raw value that is a positive number and you can use FormatHelper.ConvertDoubleToDateTime to get the date value. When you enter a 2 digit year and get the raw value, it is a negative number, and when you call FormatHelper.ConvertDoubleToDateTime it returns null.

Can you please comment on the rhyme or reason the spreadsheet behaves this way? Or is this a bug(s)?

Thanks.

Unplanned
Last Updated: 16 Oct 2026 08:01 by Wes
Created by: Wes
Comments: 0
Category: PDFViewer
Type: Bug Report
5
When printing from the Blazor PDF Viewer it is not consistent in actually preparing it to print.  Sometimes it works and sometimes it's blank pages.  This is all on the same document.  I can usually get it to work by clicking print over and over and until it renders correctly.
Planned
Last Updated: 14 Oct 2026 13:57 by ADMIN
Scheduled for 2026 (Nov)
Created by: Sebastian
Comments: 4
Category: PDFViewer
Type: Bug Report
1
  • The PDF Viewer does not display the initial file if Zoom is set to FitToWidth or FitToPage. This is due to --scale-factor: NaN; --total-scale-factor: NaN; set on the PDF Viewer element.
  • If the PDF Viewer initially shows with no loaded file, setting Zoom to FitToWidth or FitToPage initially or after opening a file leads to infinity zoom due to --scale-factor: Infinity; --total-scale-factor: Infinity; set on the PDF Viewer element.

The only scenario that works is to set the initial Zoom to a numeric value and have an open file by default.

1 2 3 4 5 6