Unable to override OnAfterRenderAsync in client side blazor

Quoting ASP.NET Core and Blazor updates in .NET Core 3.0 Preview 9's Upgrade an existing project:

• Replace OnAfterRender() and OnAfterRenderAsync() implementations with OnAfterRender(bool firstRender) or OnAfterRenderAsync(bool firstRender).

Since NET Core 3.0 Preview 9 OnAfterRender receives a boolean parameter to let method know if this is the first render. Very useful to avoid controlling it by yourself:

Sample about how to replace old code to new one, red old code, green new one.

try this

@code {
    protected override async Task OnAfterRenderAsync(bool firstRender)
    {

    }
}

Note that both OnAfterRenderAsync and OnAfterRender has a boolen parameter you may call firstRender

 protected override async Task OnInitializedAsync()
    {

    }

Indeed, that should work with no issues as this is the correct method signature of OnInitializedAsync