Predefined dialogs throw when hot reload updates are applied

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Completed

Last Updated: 01 Oct 2025 10:37 by ADMIN

Release 6.1.0

Stefan

Created on: 17 Jul 2024 15:24

Category: Dialog

Type: Bug Report

Predefined dialogs throw when hot reload updates are applied

The issue can be reproduced when clicking on a button that opens a predefined Dialog, then making some changes on the page and hot reloading. In this scenario, I get the following error:

Microsoft.JSInterop.JSException: Cannot read properties of null (reading 'addEventListener')
TypeError: Cannot read properties of null (reading 'addEventListener')

2 comments

ADMIN

Hristian Stefanov

Posted on: 01 Oct 2025 10:37

Hi Stefan,

There’s another item under your name on our public feedback portal that’s currently marked as Unplanned. It actually seems to be the one most relevant to your case. Please take a look at it and follow the thread there for future updates: https://feedback.telerik.com/blazor/1682454-predefined-dialogs-are-not-shown-after-hot-reload-updates-are-applied

Let me know if I’ve misunderstood anything.

Regards,
Hristian Stefanov
Progress Telerik

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Stefan

Posted on: 24 Sep 2025 17:39

One year later we are still seeing this after Hot Reload with .NET 9 and Telerik UI for Blazor 9.1.1

crit: Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]

Unhandled exception rendering component: Cannot read properties of null (reading 'dataset')
TypeError: Cannot read properties of null (reading 'dataset')
at new r (http://localhost:5079/_content/Telerik.UI.for.Blazor/js/telerik-blazor.js:1:1022483)
at e.initComponent (http://localhost:5079/_content/Telerik.UI.for.Blazor/js/telerik-blazor.js:23:2512410)
at e.initDialog (http://localhost:5079/_content/Telerik.UI.for.Blazor/js/telerik-blazor.js:23:1684607)
at http://localhost:5079/_framework/blazor.webassembly.js:1:2900
at new Promise (<anonymous>)
at v.beginInvokeJSFromDotNet (http://localhost:5079/_framework/blazor.webassembly.js:1:2857)
at Object.Zt [as invokeJSJson] (http://localhost:5079/_framework/blazor.webassembly.js:1:56051)
at http://localhost:5079/_framework/dotnet.runtime.ew19f13umk.js:3:33879
at Fc (http://localhost:5079/_framework/dotnet.runtime.ew19f13umk.js:3:172343)
at wasm://wasm/00b5ba72:wasm-function[288]:0x1f1e1

Original issue: Blazor WASM breaks in VS2022 after Hot Reload in UI for Blazor | Telerik Forums