Changing columns by column menu in Gantt returns error in Telerik® UI for Blazor 9.0.0

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Last Updated: 16 Jun 2025 08:19 by ADMIN

Release 2025 Q3 (Aug)

César

Created on: 10 Jun 2025 14:34

Category: UI for Blazor

Type: Bug Report

Changing columns by column menu in Gantt returns error in Telerik® UI for Blazor 9.0.0

Hello:

I am using column menu in a gantt component. In version 8.1.1 the selection of columns to display was working correctly, but when upgrading to version 9.0.0 I get an error using the same implementation. The error received is:

blazor.web.js:1 crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
      Unhandled exception rendering component: Object reference not set to an instance of an object.
System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.Blazor.Components.Common.ColumnMenu.ColumnMenu`1.<OnColumnChooserColumnVisibilityChange>d__188[[BlazorRepl.UserComponents.__Main.FlatModel, BlazorRepl.UserComponents, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
   at Telerik.Blazor.Components.Common.ColumnMenu.ColumnMenuChooser.OnApplyClick()
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

You can replicate the error from online examples just by adding or removing visible columns.
https://www.telerik.com/blazor-ui/documentation/components/gantt/gantt-tree/columns/menu

I need to use this functionality with Telerik® UI for Blazor version 9.0.0.

When is it planned to solve this error? Is there a workaround I can apply?

Regards.

1 comment

ADMIN

Dimo

Posted on: 11 Jun 2025 08:26

Hello César,

Indeed, this is a regression in Telerik UI for Blazor 9.0.0. I am converting your ticket to a public bug report and awarding you Telerik points. Please accept my sincere apologies for the trouble.

Looking at the source code, the problem should be straight-forward to resolve and we will probably release a patch in a few weeks together with some other fixes. In the meantime, I hope it's acceptable to continue using version 8.1.1, as there is no other workaround.

Regards,
Dimo
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