Planned
Last Updated: 24 Jul 2026 14:35 by ADMIN
Created by: Emma
Comments: 3
Category: Scheduler
Type: Bug Report
1

I have been having issues adding the month view to a Telerik Blazor scheduler component, when there is grouping. It gives a null reference error any time I try to switch to the month view. I also tried it using the available demo for grouping in Telerik REPL, the only difference I found between my code and the demo was that I had used the ItemsPerSlot parameter.  I added this to the demo, and was able to reproduce the error I was seeing, and I have attached the console output from the REPL demo. I believe there is either a bug with the ItemsPerSlot being used in conjunction with grouping on a scheduler component, or some instruction missing from how to set it up properly to prevent this null reference issue. 

Changed code:

<SchedulerMonthView ItemsPerSlot="5"></SchedulerMonthView>

Demo used:

Blazor Scheduler (Event Calendar) Demos - Grouping | Telerik UI for Blazor

 


Completed
Last Updated: 24 Jul 2026 13:39 by ADMIN
Release 2026 Q3 (Aug)

The Popup OnHide event does not fire if the app has previously closed the Popup instance programmatically with the Hide() method.

The issue can be reproduced in this documentation example.

Unplanned
Last Updated: 23 Jul 2026 11:12 by ADMIN
Scheduled for 2026 Q3 (Aug)

Bug report

Reproduction of the problem

(bug report only)

  1. Run this example: https://blazorrepl.telerik.com/mUOqQflm56D4xScx54
  2. Select a font in the FontFamily dropdown.
  3. Click the UnorderedList tool in the Editor’s toolbar.
  4. A bullet is added and the FontFamily tool loses its value.
  5. Click right after the added bullet.
  6. Once again select a font in the FontFamily drodown.
  7. Click the UnorderedList tool in the Editor’s toolbar to remove the bullet.
  8. The FontFamily tool loses its value.

Current behavior

(optional)
Provide additional information if the steps for reproducing the faulty behavior are not sufficient to describe the issue.

Expected/desired behavior

The FontFamily tool should keep its value when an unordered list is added/removed.

Environment

  • Kendo/Telerik version: 14.0.0
  • Browser: [all]
Unplanned
Last Updated: 22 Jul 2026 12:31 by ADMIN

Bug report

Reproduction of the problem

(bug report only)
1. Run this example: https://blazorrepl.telerik.com/cUaBGOOZ34pkp6wB57
2. Inspect the MultiSelect’s input.
3. Click within the component’s input area, to open its popup.

The issue is also reproducible in the other dropdown components: https://blazorrepl.telerik.com/GUurGmvw32oPqGYu03

Current behavior

(optional)
When the dropdown opens, an aria-controls attribute is applied to the MultiSelect’s input. Its value does not match any existing DOM element.

Expected/desired behavior

The value of the aria-controls attribute should point at an existing element (e.g., the popup’s list element: https://www.telerik.com/blazor-ui/documentation/components/multiselect/accessibility/wai-aria-support#multiselect-wrapping-element ). But in this case the MultiSelect is not bound to data and a list element is not rendered in the popup.

Environment

  • Kendo/Telerik version: 14.1.0
  • jQuery version:
  • Browser: [all ]
Completed
Last Updated: 22 Jul 2026 10:42 by ADMIN
Release 2026 Q3 (Aug)

I am using a Blazor Telerik Grid and implementing a custom TelerikCheckBoxListFilter inside a FilterMenuTemplate.

When a user opens the "Name" filter menu and types a name quickly into the search/filter box, some of the text is removed automatically.

For example, if I type "1234567890" as input, without any delay - some of the letters will be cleared and it is showing as "1246890" in the filter search box. It could be because it is searching in real time, but the user input I am typing is not carried over correctly. See the attached screenshot taken from Telerik Demo site for the above said example.

Below is the column definition I am currently using:

<GridColumn Field="@nameof(Tenant.TenantName)" Title="Name" Width="*" FilterMenuType="@FilterMenuType.CheckBoxList">
    <FilterMenuTemplate Context="context">
        <TelerikCheckBoxListFilter Data="@Model.DistinctTenantNameList"
                                   Field="@(nameof(FilterTenantName.TenantName))"
                                   @bind-FilterDescriptor="@context.FilterDescriptor">
        </TelerikCheckBoxListFilter>
    </FilterMenuTemplate>
</GridColumn>

In Development
Last Updated: 22 Jul 2026 09:41 by ADMIN
Scheduled for 2026 Q3 (Aug)
Created by: Charles
Comments: 0
Category: TextBox
Type: Bug Report
0

Description

An input with type="password" should not have a default role. See:
w3c/html-aria#422
https://w3c.github.io/html-aria/#dfn-no-corresponding-role

Steps To Reproduce

Inspect the rendering of the password input in this demo: https://demos.telerik.com/blazor-ui/textbox/password

Actual Behavior

The element renders a role="textbox" attribute.

Expected Behavior

The element does not render a role="textbox" attribute.

Browser

All

Last working version of Telerik UI for Blazor (if regression)

No response

Unplanned
Last Updated: 20 Jul 2026 12:58 by Wes
Created by: Wes
Comments: 0
Category: PDFViewer
Type: Bug Report
1

Steps to reproduce
Reproducible with UI for Blazor, as well as UI for ASP.NET Core (PDF.js and DPL processing)

  1. Open the attached file in the PDFViewer.

Actual Behavior
The content is visualized distorted, large parts of it are missing, layout is messed up.

Expected Behavior
The document content is visualized properly, as it is with: https://mozilla.github.io/pdf.js/web/viewer.html

Completed
Last Updated: 17 Jul 2026 13:25 by ADMIN
Release 2026 14.1.0 (Jul)
Created by: Hieu
Comments: 0
Category: AutoComplete
Type: Bug Report
9

The AutoComplete component does not update the category grouping header, even when the data within that group has been removed. As a result, the outdated group header remains visible until you scroll down to another group, at which point the first group header refreshes and disappears as expected.

Repro: REPL link.

Completed
Last Updated: 17 Jul 2026 13:22 by ADMIN
Release 2026 Q2

Hi Support,

I have an issue with the DragToSelect feature of a Telerik grid in Blazor when this grid is inside a TelerikWindow. 

Summary
When a TelerikGrid configured with GridSelectionSettings DragToSelect="true" is rendered inside the <WindowContent> of a <TelerikWindow>, the drag-to-select (rubber-band) behavior is not working properly — the user can only select cells/rows via individual clicks.

Single-click selection continues to work in both cases. The issue is specific to the drag gesture.

Steps to reproduce
Create a page with a TelerikWindow set to Visible="true".
Inside <WindowContent>, place a TelerikGrid with:
SelectionMode="@GridSelectionMode.Multiple"
SelectedCells / SelectedCellsChanged bound
<GridSettings><GridSelectionSettings SelectionType="@GridSelectionType.Cell" DragToSelect="true" /></GridSettings>
Open the window and try to select multiple cells by pressing the mouse button on a cell and dragging over neighboring cells.

Expected behavior
A rubber-band selection rectangle appears and all cells the pointer passes over become selected — same as when the identical grid is placed on a regular page (outside a modal window).

Actual behavior
Drag selection occur rarely. Only the single cell under the initial mousedown gets selected. The rubber-band rectangle rarely appears, and SelectedCellsChanged fires with a single descriptor instead of the full drag range.

Minimal repro (REPL-ready)
<TelerikWindow Visible="true" Width="800px" Height="500px">
    <WindowTitle>Repro</WindowTitle>
    <WindowContent>
        <TelerikGrid Data="@Data" TItem="SampleItem"
                     SelectionMode="@GridSelectionMode.Multiple"
                     SelectedCells="@SelectedCells"
                     SelectedCellsChanged="@((IEnumerable<GridSelectedCellDescriptor> c) => SelectedCells = c)">
            <GridSettings>
                <GridSelectionSettings SelectionType="@GridSelectionType.Cell" DragToSelect="true" />
            </GridSettings>
            <GridColumns>
                <GridColumn Field="@nameof(SampleItem.Id)" />
                <GridColumn Field="@nameof(SampleItem.Name)" />
            </GridColumns>
        </TelerikGrid>
    </WindowContent>
</TelerikWindow>

@code {
    public record SampleItem(int Id, string Name);
    private List<SampleItem> Data = Enumerable.Range(1, 20).Select(i => new SampleItem(i, $"Item {i}")).ToList();
    private IEnumerable<GridSelectedCellDescriptor> SelectedCells = Enumerable.Empty<GridSelectedCellDescriptor>();
}

Now my questions :
- Is this a known limitation of DragToSelect when the grid is inside a modal TelerikWindow?
- Is there an officially supported workaround (CSS pointer-events tweak on .k-overlay, event capture override, grid setting, etc.)?
- If it is a bug, could you open a public issue we can track?

Many thanks you in advance.

Franck Boisdé

Planned
Last Updated: 17 Jul 2026 13:19 by ADMIN
Scheduled for 2026 Q3 (Aug)

Description

Appointment editing does not work on Chrome for mobile (Android).

Steps To Reproduce

Run the following demo in the Chrome for mobile browser, on a mobile device with Android : https://demos.telerik.com/blazor-ui/scheduler/appointment-editing

  1. Attempt to edit an appointment by double tapping it

Actual Behavior

The popup editor does not show up.

Expected Behavior

The popup editor shows up.

Browser

Chrome

Last working version of Telerik UI for Blazor (if regression)

No response

Planned
Last Updated: 17 Jul 2026 12:35 by ADMIN
Scheduled for 2026 Q3 (Aug)

Bug report

Reproduction of the problem

(bug report only)
Regression introduced in 13.0.0.
1. Run this example: https://blazorrepl.telerik.com/wUuSGClv00orFeRm59

Current behavior

(optional)
The Size, Rounded, FillMode parameters are ignored.

Expected/desired behavior

The parameter values should apply and change the appearance of the SearchBox.

Environment

  • Browser: [all ]
Completed
Last Updated: 17 Jul 2026 11:28 by ADMIN
Release 2026 14.1.0 (Jul)
Created by: Niraj
Comments: 0
Category: PivotGrid
Type: Bug Report
1
The PivotGrid row and column filtering is case sensitive. This makes the algorithm inconsistent with the other filtering features in Telerik UI for Blazor.
Completed
Last Updated: 17 Jul 2026 11:26 by ADMIN
Release 2026 Q3 (Aug)

I am testing with a Blazor WASM Standalone app that uses Telerik UI for Blazor. I have a sample page with a button on click of which a predefined dialog (for example, alert) is shown. If you make some change on the page and hot reload is enabled, the button click no longer opens the predefined dialog. The dialog is shown only if I navigate to a different page.

Completed
Last Updated: 17 Jul 2026 11:24 by ADMIN
Release 2026 Q3 (Aug)

The Set button should not be enabled when you change the month from the button in the popup, until the user selects a date too. 

===

TELERIK EDIT:

If the user clicks Set without selecting a date, the component will assume DateTime.MinValue. You can set the current DateTime or clear the Value by using the DateTimePicker OnChange or ValueChanged event:

<TelerikDateTimePicker @bind-Value="@DateTimePickerValue"
                       OnChange="@DateTimePickerValueChanged"
                       Width="300px">
</TelerikDateTimePicker>

@code {
    private DateTime? DateTimePickerValue { get; set; }

    private void DateTimePickerValueChanged(object currentValue)
    {
        if (DateTimePickerValue.HasValue && DateTimePickerValue.Value == DateTime.MinValue)
        {
            // Set current DateTime
            DateTimePickerValue = DateTime.Now;

            // OR

            // Clear the value
            //DateTimePickerValue = default;
        }
    }
}

Completed
Last Updated: 17 Jul 2026 08:23 by Meindert
Release 2026 14.1.0 (Jul)
When you set the AutoCorrectParts parameter to false, you can no longer select a new value from the calendar popup. The date jumps back to the old date.
Completed
Last Updated: 17 Jul 2026 06:09 by ADMIN
Created by: David
Comments: 0
Category: DropDownList
Type: Bug Report
9

In TelerikSelectBase that the DropDownList inherits, the FieldIdentifier is set only in the OnInitializedAsync method and therefore the FieldIdentitier is never updated. This can cause issues with validation as seen in this example:  https://blazorrepl.telerik.com/GyamPdlf37LXpPAW36.

To reproduce:

  • Select the last item in the tree 7.Garden and change the value in the drop down list to Unsupported - the drop down list shows a red border.
  • Select item 6.Garden from the tree. (Any item in the tree other than 1 will do) - I expect the drop down to not have the red border, yet is does.

For reference, in the TelerikInputBase, the FieldIdentifier is set in the SetParameterAsync and thus it is accordingly updated. See the TextBox behavior in the above sample.

Unplanned
Last Updated: 16 Jul 2026 07:14 by ADMIN

The NumericTextBox does not render the new Value that is set in ValueChanged if this new value is different than the event argument. Instead, the component clears the textbox, even though the component Value parameter is correct.

https://blazorrepl.telerik.com/wzaAHYas221go9xd48

The problem occurs only if there is an existing value and the user removes it with Backspace.

Need More Info
Last Updated: 16 Jul 2026 06:58 by ADMIN
# Telerik UI for Blazor — TabStrip bug report

Two related defects in `TelerikTabStrip` when the tab headers wrap onto multiple rows.
Filed for GLS (Governance & Legislative System), the resolution submission form
(`/submit-resolution`), which has 12 tabs.

## Environment

- **Telerik UI for Blazor:** v14 (please fill in the exact build number from your
  `LegislationApplications` package reference before submitting)
- **.NET:** 10.0
- **Render mode:** Blazor **Server** (Interactive Server), no WebAssembly
- **Browser:** reproduced in Chromium-based browsers on a wide (≥1200px) window
- **Component config (abridged):**
  ```razor
  <TelerikTabStrip @bind-ActiveTabId="ActiveTabId"
                   PersistTabContent="true"
                   OverflowMode="TabStripOverflowMode.None"   @* wide screens *@
                   ScrollButtonsPosition="TabStripScrollButtonsPosition.Split"
                   ScrollButtonsVisibility="TabStripScrollButtonsVisibility.Auto">
      @* 12 TabStripTabs; several use Visible="@boolExpr" (conditionally shown);
         most use a <HeaderTemplate> that renders the title plus an optional indicator icon *@
  </TelerikTabStrip>
  ```
- On a wide window with `OverflowMode="None"`, the 12 tab headers **wrap onto two rows**
  (row 1 ends at "Budget Impact"; row 2 begins at "OGR Consultation").

---

## Bug 1 — Wrapped tabs: activating a tab at the wrap boundary shows the WRONG content panel

### Repro
1. Open a form whose tab headers wrap to two rows (wide window, `OverflowMode="None"`, enough
   tabs to force a second row).
2. Activate the tab that sits at the **end of the first row** (its immediate left neighbour is on
   the same row; its right neighbour is on the next row). In our form: activate **External
   Documents**, then click **Budget Impact** (last tab on row 1).

### Expected
Budget Impact’s content panel is displayed.

### Actual
- The Budget Impact **header** receives focus/active styling, but the **content area still shows
  the previous tab’s panel** (External Documents).
- It is **deterministic** from the left-neighbour: a 2-second pause before clicking does **not**
  help.
- **Workarounds that do make it switch:** double-clicking the tab, or first activating a tab on a
  **different row** (e.g. OGR Consultation) and then clicking Budget Impact once.

### Proof the server/binding side is correct (it is a client-side rendering defect)
We instrumented the `ActiveTabId` setter and component renders. On the failing single click:
```
ActiveTabId 'tab-submitter'          -> 'tab-external-documents'   (click External)
RENDER  activeTab=tab-external-documents
ActiveTabId 'tab-external-documents' -> 'tab-budget-impact'        (click Budget Impact)
RENDER  activeTab=tab-budget-impact
(no further activity)
```
So `ActiveTabIdChanged` fires with the correct id, `ActiveTabId` becomes `tab-budget-impact`, and
the component re-renders exactly once with the correct active tab — yet the browser keeps showing
the External Documents content panel. The subsequent “rescue” clicks that fix the display produce
**no** server activity at all, confirming the mismatch is purely in the component’s client-side
content-panel switching.

### Confirmed trigger: the wrapping
Forcing the tab headers onto a **single row** with CSS (no other change) makes the bug disappear
entirely — every tab activates its correct panel on the first click:
```css
.k-tabstrip-items-wrapper { flex-wrap: nowrap; overflow-x: auto; }
.k-tabstrip-items         { flex-wrap: nowrap; }
```
This is not an acceptable final fix for us (the product requires the wrapped, all-tabs-visible
layout), but it isolates the cause: **`TelerikTabStrip` mismaps the active content panel when its
headers wrap to more than one row.**

---

## Bug 2 — `OverflowMode="Scroll"` throws an exception for this configuration

### Repro
Set `OverflowMode="TabStripOverflowMode.Scroll"` (instead of `None`) on the same TabStrip
(12 tabs, `PersistTabContent="true"`, several tabs with `Visible="@expr"` including one that is
currently `Visible="false"`, and `<HeaderTemplate>`s).

### Actual
The page throws an unhandled exception on load / render (Blazor error UI). Reverting to
`OverflowMode="None"` removes the exception.

> **To complete this section before filing:** capture the exact exception type, message, and the
> top Telerik stack frames from the browser DevTools console or the app’s server log (Aspire
> dashboard → `legislationwebapp` resource) while `OverflowMode="Scroll"` is active. We suspect it
> relates to scroll-width measurement of a `Visible="false"` tab and/or `HeaderTemplate` tabs, but
> the stack trace will confirm.

---

## Why this matters / requested outcome

- Bug 1 forces a poor workaround (users must double-click or approach tabs from a specific
  direction) or a UX compromise (single-row scrolling instead of the required wrapped layout).
- Bug 2 blocks the natural single-row fix (`OverflowMode="Scroll"`).

We would like `TelerikTabStrip` to either (a) correctly map the active content panel when headers
wrap, or (b) provide a supported single-row/wrapping option that does not throw for this
configuration.
Completed
Last Updated: 15 Jul 2026 10:43 by ADMIN

Hi,

  Using VS code I tried to create a project using the latest Telerik UI for Blazor Productivity tools.  Updated 24-12-03

  The Error:

Completed
Last Updated: 14 Jul 2026 08:44 by ADMIN
Release 2026 14.1.0 (Jul)
Created by: Adam
Comments: 1
Category: Grid
Type: Bug Report
1

The Grid performance worsens progressively with each subsequent edit operation. Please optimize that.

Test page: https://blazorrepl.telerik.com/mJuHFNbb17FpJu9b54

Click on a Price or Quantity cell to start edit mode and tab repetitively to observe the degradation.

1 2 3 4 5 6