Last Updated: 29 May 2023 11:12 by ADMIN


We have found a strange issue that I have created a REPL to reproduce:

1. Select a .doc file

2. Select a second file

3. Click the "Copy Memory Stream" Button

the method stops at CopyToAsync for the .doc file

It seems to work fine if the files are selected together or if different file types are used

I have been testing with the attached .doc and a blank .txt file

Last Updated: 29 May 2023 09:15 by Stewart
Created by: Stewart
Comments: 3
Category: DateTimePicker
Type: Bug Report


I have a REPL showing the issue.

I am using DataAnnotation where possible in my application and I was expecting the DisplayFormat attribute to be applied in the DateTimePicker like it is for DatePicker but as shown in the REPL link below it's not. I will use a workaround of applying the Format attribute everywhere but I would appreciate this being changed.

Last Updated: 29 May 2023 07:56 by ADMIN
Release 4.3.0 (06/07/2023) (R2 2023)

The problem is reproducible in your demo section:

I attached two short video clips showing the problem and the screenshots below.

Image 1: Open the Color Picker by clicking on it with the mouse. The picker dialog opens.

Image 2: Click with the mouse in the green area. You see a minor change in the RGBA fields, but no change in the color canvas.

Image 3: By clicking in the G field e.g. and changing the number with the down key from 46 to 45, the slider moves back to the blue area of it.

It seems to happen only with the first click onto the slider. With the second click and more it works like it should.

Best regards,

Last Updated: 25 May 2023 13:05 by Martin

The issue is reproducible when the `AllowCustom` parameter is set to `true`.
Typing rapidly in the input field of the MultiColumnComboBox component causes the entered text to blink. Also, some of the inserted symbols are cleared.

Reproduction (if bug)

Open this demo:

Try to input text rapidly into the input field.

Last Updated: 24 May 2023 10:51 by ADMIN

from this screenshot from the demo selecting a value via the keyboard leaves the box blank

to replicate press the down arrow when MultiColumnComboBox has focus

Last Updated: 24 May 2023 10:22 by ADMIN
Created by: Ivaylo
Comments: 1
Category: UI for Blazor
Type: Bug Report

Hello there,

I encountered an issue with the TelerikGrid component. This started to be an issue from version 4.1.0 and can be reproduced from here:

If this line from the example:

<GridColumn Field=@nameof(SampleData.Name) Title="Name" />
is changed to:

<GridColumn Field=@nameof(SampleData.Name) Title="Name" Visible="@!isVisible">
       @((context as SampleData).Name)

you can see that once the template GridColumn is shown, its data overwrites the data of the "Hire Date" column when toggling the visibility of the columns. The header of the column is changing but the data stays the same.

To provide a visual context of the issue, I have attached a video.


Best regards,


Last Updated: 24 May 2023 08:51 by ADMIN
Scheduled for 4.3.0 (06/07/2023) (R2 2023)

I have a page with a Gantt chart and a Button. The button navigates to another page in the app (NavigationManager.NavigateTo()). When I click the button an exception is thrown:

Exception trace: Error: Microsoft.JSInterop.JSException: An exception occurred executing JS interop: The JSON value could not be converted to System.Double. Path: $ | LineNumber: 0 | BytePositionInLine: 4.. See InnerException for more details. ---> System.Text.Json.JsonException: The JSON value could not be converted to System.Double. Path: $ | LineNumber: 0 | BytePositionInLine: 4.
 ---> System.InvalidOperationException: Cannot get the value of a token type 'Null' as a number.

Last Updated: 23 May 2023 15:35 by jordan

I am trying to programmatically update the Chart data during runtime to display live data. The Chart does not seem to refresh and show this change in the viewport.

I've tried:

  • using an Observable Collection;
  • creating a new collection instance and reassigning the Data parameter;
  • calling the Refresh method;

The result is the same - the Chart does not react to the data change. This applies to other component parameters as well.




A possible workaround for the time being is forcing the Chart to re-render. To do so, you may wrap the Chart in a custom component and call StateHasChanged() in this component when the data is updated.

Here is a runnable sample:
Need More Info
Last Updated: 22 May 2023 09:37 by ADMIN

Grid with columns price1 and price2. Enter value in price1, switch to price2, enter value there, and editor is set to old value after async events finish.

The value entered in price2 is correctly set to the property, but the editor reverts to the previous value. If you escape edit mode of the cell, the value entered before the events finish will be shown.

On (fast) tabbing and entering values, this removes the first values entered before the async background events finish.

I tried reproducing the problem in REPL, but could not get the exact same behaviour. In our case no specific value is being set to price2, it just reverts.


How would you approach preventing the editor from being overridden by other cells' delayed events?

Last Updated: 18 May 2023 15:09 by ADMIN
Created by: Andre
Comments: 7
Category: Grid
Type: Bug Report
The Grid footer row will not scroll horizontally if:
  • the Grid is initially rendered without columns
  • I am using OnInitializedAsync

Here is a runnable REPL test page. A possible workaround is to render the Grid only if it has columns:

    if (GridColumns.Count() > 0)
        <TelerikGrid Data="@Data">
                @foreach (var column in GridColumns)
                    <GridColumn Field="@column.DataField"
                                ShowColumnMenu="false" Title="@column.DisplayName" Resizable="true" Width="500px">
Last Updated: 18 May 2023 07:41 by ADMIN
Created by: Kimmie
Comments: 0
Category: DropDownList
Type: Bug Report

The DropDownList remains open after tabbing and does not fire. It also won't fire OnBlur and OnChange in this case. The problem occurs only if the component was opened by clicking exactly on its arrow.

Here is a test page:

The workaround is to wrap the component in a <span> that handles @onfocusout and closes the component programmatically:

Last Updated: 16 May 2023 14:59 by ADMIN
Created by: John
Comments: 1
Category: DateTimePicker
Type: Bug Report



Just reporting this as an active bug. If I have a nullable DateTime object, and I erased the date on the date time picker, it treats the date time field as invalid. I would expect it to be treated as valid.

Related thread:

This is the razor page:

<TelerikDatePicker Id="@Id"
Last Updated: 16 May 2023 14:18 by David

When initial grouping is set through the state, the GroupFooterTemplate does not render. One has to perform some action for refreshing the Grid in order to display the template - for example, collapsing/expanding a group.

For reference, the GroupHeaderTemplate renders correctly.





The GroupFooterTemplate renders with a delay after the Grid. A possible workaround for the time being is to refresh the Grid after it has been initialized to ensure the GroupFooterTemplate will be displayed.


Last Updated: 12 May 2023 13:05 by Simon
I want my users to confirm the update of a cell value with the built-in Confirmation Dialog for Blazor. If I use the keyboard (Enter, Tab) to close the edit the Confirmation dialog will popup, but after closing it the Grid hangs. 
Last Updated: 12 May 2023 07:20 by ADMIN
Release 4.3.0 (06/07/2023) (R2 2023)


I noticed that using left or right arrow to position yourself between typed text does not work anymore in the GridSearchBox. Neither does SHIFT+left for selecting parts of typed text. Home or End key is also not working.


In previous versions this was still possible.


Can be estabished on the demo pages as well:




Last Updated: 11 May 2023 11:48 by Ron Hary
The OnCellRender event is executed more times than expected.
Last Updated: 10 May 2023 13:42 by Sara

Description : 
When you click before the content in the Editor, the cursor should show up before the text. But, if a text was added programmatically, the cursor shows up after the added text instead.

To reproduce the problem :

1. Open this REPL example:

2. Click the "Insert Inline Text" button.

3. Try to place the cursor in front of the editor content.

Last Updated: 09 May 2023 13:27 by Constantinos Petridis

I have a ComboBox/DropDownList that gets data from a remote service, using virtualization. When the PageSize property is big enough (in my case 20), I have issues scrolling up the selection box dropdown list. I'm trying to scroll but then resets to the currently selected item making it almost impossible to scroll up. You can use your own demo examples to replicate this issue.

To reproduce the issue, try the ComboBox - Virtualization, in Telerik REPL (Demo), change the PageSize from 10 to 20. Open the dropdown and select an item. Then, open again the dropdown and scroll slowly up.

Last Updated: 09 May 2023 12:13 by ADMIN
Created by: Robert
Comments: 1
Category: UI for Blazor
Type: Bug Report

When trying to expand the drop downs, some of them do not expand.
It is impossible to give a scenario that always behaves the same, but if
you keep expending the drop downs sooner or later some will stop working.

Last Updated: 08 May 2023 10:35 by Nate

Try to click an item in the context menu by clicking the icon instead of the text. The click doesn't register. It happens only with SVG icons.

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