Last Updated: 24 Apr 2024 19:52 by David
Created by: Simon
Comments: 4
Category: PDFViewer
Type: Bug Report


i want to Render PDF Files with the PDF Viewer Component.

The Data of the PDF is already fetched from the API when the PDF-Viewer starts Rendering the Loading animation appears and freezes.

After a few Seconds the PDF will be Rendered.

The size of the PDF File is about 5MB.



Last Updated: 24 Apr 2024 14:27 by ADMIN
Created by: Matthijs
Comments: 3
Category: DropDownList
Type: Bug Report

Steps to reproduce:

  1. Open the Edit in Telerik REPL link from the demo page for DropDownList - Grouping.
  2. Add Filterable="true" to TelerikDropDownList.
  3. Run.
  4. Open the dropdown.
  5. Type in for instance the last item of the list "Röd Kaviar", that belongs to the category "Seafood".

Expected: the group name should change to "Seafood".

Actual: the group name is still "Beverages".

Pending Review
Last Updated: 22 Apr 2024 18:50 by Scott
Created by: Scott
Comments: 0
Category: Grid
Type: Bug Report

On grids with a lot of data there is a delay between when the grid is assigned the data to when the grid shows the data.  During this UI painting period, the NoDataTemplate is displayed for a second or two.

The grid should not show the NoDataTemplate unless the data source is loaded with an empty collection, not just while it is still trying to show the data.

Note: Having a generic message like in the documentation "No Data available / The data is still loading ..." is not satisfying our users. (Blazor Grid - No Data Template - Telerik UI for Blazor) These should really be two different states that can show different messages.


Last Updated: 22 Apr 2024 16:08 by ADMIN
Release 2024 Q2 (May)
I am opening a standard PDF document and it is not properly displayed in the PDF Viewer. For example, you can see the logo and the table borders but the text of the PDF is missing. If you open the same document in a normal Adobe viewer it is fine.
Last Updated: 22 Apr 2024 14:34 by Frank
Created by: Frank
Comments: 0
Category: Window
Type: Bug Report

The Window can display as centered, but after the user moves or resizes it, the app is not able to center the Window programmatically.

The only possible workaround is to toggle the Window's Visible parameter:


<TelerikWindow @bind-Top="@Top" @bind-Left="@Left" Centered="@Centered" @bind-Visible="@Visible">
        Drag or resize the Window and center it afterwards...

<TelerikButton OnClick="@( () => Visible = !Visible )">Toggle Window</TelerikButton>
<TelerikButton OnClick="@OnCenterClick">Center</TelerikButton>

@code {
    string Top { get; set; }
    string Left { get; set; }
    bool Centered = false;
    bool Visible { get; set; } = true;

    async Task OnCenterClick()
        Visible = false;
        await Task.Delay(1);

        Top = Left = string.Empty;
        Visible = true;

Last Updated: 22 Apr 2024 09:54 by ADMIN
Release 2024 Q2 (May)


I have found a bug with the TelerikNumericTextBox in that it doesn't function correctly with nullable types (at least it doesn't with Nullable<int>). I have confirmed this is the case for both 2.28 and 2.29 versions of Kendo for Blazor.

Description of the issue:

If "TelerikNumericTextBox" is "@bind-Value" to a nullable int, the control exhibits some unusual behaviour. If you manually type 0 into the control, it is accepted and the value updates the view-model property. However, if you use either the down-arrow button or arrow keys to select 0 (on a fresh load so there is no existing value selected/set), it does not set/update the view-model property. However, it does work correctly if you select another value first (such as 1) and then select 0.

Unfortunately, this is confusing the end-users of my application and I believe it is a bug (I haven't noticed this when using the Kendo for Angular or Kendo for JQuery).

In my application, I need users to be able to set the value of 0 but we do not want to set an initial value for the NumericTextBox to be 0 as this could lead our customers on; the application in question is requiring the end-user to manually select the number rather than allowing them to just leave it as default. Therefore, the view-model property I am binding to has been put as "int?" so that the default value is null and validation will require the user to select a valid value if they just try and press save without making any changes. Please note, for our use case, the number 0 is a valid option!

Steps to reproduce the issue:

Use the following razor HTML

The new value is: @TheValue

<TelerikNumericTextBox Format="D" Max="10" Min="0" Step="1" @bind-Value="@TheValue"></TelerikNumericTextBox>

@code {
    public int? TheValue { get; set; }

Click into the control and either press "down" on the keyboard arrow keys or press the "down" icon next to the control, so the value is set to be 0. The number 0 will not be set/persisted to the view-model property even though the control shows a 0 value.

If you have multiple controls on the page, following the above steps will mean that as soon as you click into another control, 0 is deleted (I believe because the VM prop has not been set), this does not happen if you type 0 into the control.


If you continue to use the same Razor code above and any of the following workflows, it will set the controls view-model property correctly:

  • Type 0 into the control - value is set correctly and property on the view-model is updated
  • Select "up" on the keyboard (so the value is 1) and then press down (so the value is 0) - 0 is set correctly and property on the view-model is updated
  • Select "up" on the numeric textbox's up arrow button (so the value 1) and then press "down" on the down arrow button (so the new value is 0) - 0 is set correctly and property on the view-model is updated

Additional notes:

  • I have noticed this only seems to apply to the nullable version of the int type, if the prop is just an int, the control works fine but is automatically defaulted to 0 (which is not appropriate for my use case)
  • It seems that as soon as the control/view model property has an initial value, the control behaves normally and the issue no longer happens anymore (both with keyboard navigation and the control's up/down buttons).
  • I have not tested with any other types/primitives, just on INT so far
  • I have confirmed this happens if you have the control in an "<EditForm/>" or outside of an EditForm. 

I have attached a sample project where I have replicated the issue, it is just a simple NET5 WASM Blazor project (generated from the default template) and I have just added the latest Kendo for Blazor. Nothing else has been done except for demoing on the "index.razor" both binding approaches I have tried/been able to replicate this issue on.


I hope the above makes sense, let me know if you need any further clarification.

Last Updated: 22 Apr 2024 07:47 by ADMIN
Release 2024 Q2 (May)

Hi Telerik team,


When I want to bind the Blazor Grid to an ExpandoObject I need to assign the FieldType. I know I have to use non-nullable types.

But I want to use nullable types (for example int?) to have a blank cell within the Grid when there is no value for it. With "typeof(int)" instead of "typeof(int?)" every empty cell shows "0" which I don't want.

Is there any chance to let FieldType accept nullable types?


Best regards,


Last Updated: 18 Apr 2024 22:46 by Marc
Release 2024 Q2 (May)
Created by: Srdjan
Comments: 10
Category: PDFViewer
Type: Bug Report
If you compare the print quality against the Kendo UI jQuery PDF viewer, the quality difference is night and day. We did not investigate what is happening under the hood in both components. However, the same printing dialog appears when printing via both components and both of them are web components, which indicates to us, that this issue is not related to the browser.
Last Updated: 18 Apr 2024 17:44 by Nicholas
I modified this sample app: https://github.com/telerik/blazor-ui/tree/master/grid/datasourcerequest-on-server/WebApiFromServerApp.

I am trying to add aggregation to the grouping and display them in the group footers. I am successfully returning the aggregated values but they are not displayed in the GroupFooterTemplate.
Last Updated: 18 Apr 2024 11:41 by ADMIN
Release 2024 Q2 (May)
Created by: Mike
Comments: 1
Category: Form
Type: Bug Report

When I assign an Id to a FormGroup in TelerikForm, it's value can be seen in code, but neither the attribute nor it's value get rendered.


<TelerikForm Model="@TestUser"
                <FormGroup LabelText="User Information" Id="userinfo">
                    <FormItem Field="@nameof(User.FirstName)"></FormItem>
                    <FormItem Field="@nameof(User.LastName)"></FormItem>
                    <FormItem Field="@nameof(User.Email)">
                            <label for="mail" class="k-label k-form-label">Email*:</label>
                            <TelerikTextBox Id="mail" @bind-Value="@TestUser.Email" InputMode="email" Placeholder="example@domain.com"></TelerikTextBox>
                            <TelerikValidationMessage For="@(() => TestUser.Email)"></TelerikValidationMessage>
                    <FormItem Field="@nameof(User.Password)">
                            <label for="pass" class="k-label k-form-label">Password*:</label>
                            <TelerikTextBox Id="pass" @bind-Value="@TestUser.Password" Password="true"></TelerikTextBox>
                            <TelerikValidationMessage For="@(() => TestUser.Password)"></TelerikValidationMessage>
                    <FormItem Field="@nameof(User.BirthDate)" />
                    <FormItem Field="@nameof(User.AcceptTerms)" />
                <FormGroup LabelText="Shipping Address" Id="shipaddress">
                    <FormItem LabelText="Country*: " Field="@nameof(User.Country)" />
                    <FormItem LabelText="City*: " Field="@nameof(User.City)" />
                    <FormItem LabelText="Address Line*: " Field="@nameof(User.AddressLine)" />
                    <FormItem LabelText="Second Address Line: " Field="@nameof(User.AddressLine2)" />
Last Updated: 18 Apr 2024 11:34 by ADMIN
Release 2024 Q2 (May)

When the MultiColumnComboBox columns are rendered with a foreach loop, the component doesn't remove columns that are no longer defined.

The workaround is to recreate the MultiColumnComboBox: https://blazorrepl.telerik.com/wSOIvzvR46lEZrwy43


Last Updated: 18 Apr 2024 10:23 by ADMIN
Scheduled for 2024 Q2 (May)

The null type of operator can cause errors on the backend

*** Thread created by admin on customer behalf ***

Need More Info
Last Updated: 17 Apr 2024 15:58 by ADMIN
<TelerikDateTimePicker Value="@AttendanceDTO.WorkScheduleEndTime"
                       ValueExpression="@(() => AttendanceDTO.WorkScheduleEndTime)"
                       ValueChanged="@( (DateTime d) => ChangeWorkScheduleEndTime(d) )"
                       Format="dd/MM/yyyy (dddd) HH:mm"
Last Updated: 17 Apr 2024 11:35 by Michael
Created by: Michael
Comments: 0
Category: Charts
Type: Bug Report
The Chart Tooltip does not respond to the applied Globalization settings. In the Chart Globalization demo change the culture to German, hover over a data point of the Line series, and note that the decimal separator is a dot (".") and not a comma (",") as expected. 
Last Updated: 12 Apr 2024 16:04 by ADMIN

On Hierarchy grids with Inline edit mode, I noticed that if a row is currently being edited and I try to expand the row to show the child grid an exception is thrown: "Error: System.InvalidOperationException: TelerikValidationComponent requires a cascading parameter of type EditContext. You can use Telerik.Blazor.Components.TelerikValidationTooltip`1[System.String] inside a EditForm or TelerikForm".

The problem stems from a validation tool inside the Grid EditorTemplate.

Last Updated: 12 Apr 2024 15:40 by ADMIN
Release 2024 Q2 (May)

There is a change in the Grid behavior from version 4.6.0 to 5.0.0.

Consider the following REPL test page: https://blazorrepl.telerik.com/cSabmRPy306iPiXK18

Clicking on a Grid cell for editing will not open it for editing if there is already an open cell in edit mode on the same table row. The issue is reproduced more easily if the OnUpdate handler is empty or not defined at all.

This used to work in version 4.6.0.

Last Updated: 11 Apr 2024 14:11 by Plastic

When a user deletes a record that decreases the number of pages on that Grid, and then they try to edit or add a record, they get stuck in the OnCancel event handler, which gets called over and over in an endless loop.

The behavior can be seen:

  • After deleting a record in the Grid, which decreases the number of pages.
  • The Grid is using a confirmation dialog from the DialogFactory for the Cancel action.

Steps To Reproduce


1. Delete item 11. The Grid will move you to page 1.
2. Try to edit or add a new item. OnCancel will fire in a loop.
3. If OnAdd and OnEdit are not defined, the loop will occur in OnUpdate and OnCancel.

Last Updated: 11 Apr 2024 08:10 by ADMIN
Release 2024 Q2 (May)

Hey Telerik team,

We encountered issue with DateTime picker which I was able to reproduce in your Documentation preview.

If you hover over the date time dropdown, but really slowly it bugs out and the view becomes unusable like this:

As you can see, the dropdown is messed up and it seems like the hover over the border is trying to trigger some action to change from date to time pick automatically



Last Updated: 09 Apr 2024 18:42 by Gerald
Created by: Taarti
Comments: 0
Category: Grid
Type: Bug Report

In the case of a sorted column, NVDA is not narrating the correct column name and narrating the incorrect Roles for the column headers.

In the case of an unsorted column, NVDA is narrating the column name twice and repeating the information.

Last Updated: 09 Apr 2024 09:32 by ADMIN
Created by: Kacper
Comments: 1
Category: UI for Blazor
Type: Bug Report

I have a little problem with changing the LoadGroupsOnDemand value. Depending on the data in my grid, I set this value to true or false. When updating grid data requires changing the LoadGroupsOnDemand value, I can't do it this way:

LoadGroupsOnDemand = true;
GridData = result;

This code throws me an exception.
I need to do something like this to make it work:

LoadGroupsOnDemand = true;
GridRef.LoadGroupsOnDemand = LoadGroupsOnDemand;
GridData = result;

This is the code that is executed in onclick. After OnRead is executed, the exception is thrown.

Let me know if you need more information.

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