❗ Issue After Upgrading to Radzen 7.0.5 — RadzenChartTooltip Throws JS Error on Hover

Radzen.Blazor Components
1

Hello,

I recently upgraded my project from Radzen version 5 to 7.0.5, and I encountered a JavaScript error when hovering over a column chart that uses <RadzenChartTooltip />.

:package: Project Setup

We're using an older project structure that includes:

  • _Host.cshtml
  • App.razor
  • Index.razor

In _Host.cshtml, we render the root component with server-side render mode:

@(await Html.RenderComponentAsync<App>(RenderMode.Server, new { IPAddress = Model.IpAddress }))

And we include these scripts:

<script src="_framework/blazor.server.js" autostart="false"></script>
<script src="_content/Radzen.Blazor/Radzen.Blazor.js"></script>
<script src="js/script.js"></script>

:gear: App.razor and Layout Details

  • App.razor uses the default <Router> with <RouteView>.
  • In MainLayout.razor, we define our layout and include:
<RadzenTooltip />
<RadzenChartTooltip />

:x: Problem

When hovering over a column chart, this error appears in the console:

[2025-05-23T06:07:50.983Z] Error: Microsoft.JSInterop.JSException: Could not find 'Radzen.openChartTooltip' ('openChartTooltip' was undefined).
Error: Could not find 'Radzen.openChartTooltip' ('openChartTooltip' was undefined).

Uncaught (in promise) Error: Cannot send data if the connection is not in the 'Connected' State.
    at on.send (blazor.server.js:1:81941)
    ...
    at HTMLDivElement.<anonymous> (Radzen.Blazor.js:1204:18)

:page_facing_up: Chart Definition Snippet

Here's how we're defining the chart component:

<RadzenColumnSeries Data="@x" CategoryProperty="CurrencyCode" Title="x" ValueProperty="Amount">
    <TooltipTemplate Context="data">
        <div>
            <strong>Gross Written Premium: @data.Amount.ToString("N2") @data.CurrencyCode</strong>
        </div>
    </TooltipTemplate>
</RadzenColumnSeries>

:white_check_mark: What We've Already Done

We’ve followed the documentation for using Radzen components with interactive server mode. Specifically:

  • Added <RadzenComponents @rendermode="InteractiveServer" /> in MainLayout
  • Confirmed Radzen.Blazor.js is referenced in _Host.cshtml

:question: What’s Not Working

Despite this, hovering over the chart causes the error and tooltips do not show.

:point_right: Question

Is there any additional step required in version 7.0.5 to enable RadzenChartTooltip properly?
Is it possible this is a version-related issue or a missing initialization due to how scripts are loaded?

Would really appreciate any guidance to fix this.

Thanks in advance!

2

Getting this JavaScript error means that you are using an old (cached) version of Radzen.Blazor.js. Check the getting started instructions to find how to include the script in such a way that it is never again stale.

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