System.AggregateException: Exceptions were encountered while disposing components. (Cannot process pending renders after the renderer has been disposed.
Object name: 'Renderer'.) (Cannot process pending renders after the renderer has been disposed.
Object name: 'Renderer'.)
 ---> System.ObjectDisposedException: Cannot process pending renders after the renderer has been disposed.
Object name: 'Renderer'.
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessPendingRender()
   at Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer.ProcessPendingRender()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(Int32 componentId, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()
   at Telerik.Blazor.Components.Common.BaseComponent.StateHasChanged()
   at Telerik.Blazor.Components.TelerikButtonGroup.Telerik.Blazor.Components.ButtonGroup.IButtonContainer.RemoveButton(ButtonGroupButtonBase button)
   at Telerik.Blazor.Components.ButtonGroup.ButtonGroupButtonBase.Dispose()
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.Dispose()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.Dispose(Boolean disposing)
   --- End of inner exception stack trace ---
 ---> (Inner Exception #1) System.ObjectDisposedException: Cannot process pending renders after the renderer has been disposed.
Object name: 'Renderer'.
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessPendingRender()
   at Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer.ProcessPendingRender()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.AddToRenderQueue(Int32 componentId, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.ComponentBase.StateHasChanged()
   at Telerik.Blazor.Components.Common.BaseComponent.StateHasChanged()
   at Telerik.Blazor.Components.TelerikButtonGroup.Telerik.Blazor.Components.ButtonGroup.IButtonContainer.RemoveButton(ButtonGroupButtonBase button)
   at Telerik.Blazor.Components.ButtonGroup.ButtonGroupButtonBase.Dispose()
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.Dispose()
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.Dispose(Boolean disposing)

@inject IJSRuntime JsInterop

<TelerikGrid Data="@salesTeamMembers" OnRowClick="@OnRowClickHandler" @ref="@GridRef">
    <DetailTemplate>
        @{
            var employee = context as MainModel;
            <TelerikGrid Data="employee.Orders" Pageable="true" PageSize="5">
                <GridColumns>
                    <GridColumn Field="OrderId"></GridColumn>
                    <GridColumn Field="DealSize"></GridColumn>
                </GridColumns>
            </TelerikGrid>
        }
    </DetailTemplate>
    <GridColumns>
        <GridColumn Field="Id"></GridColumn>
        <GridColumn Field="Name"></GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    List<MainModel> salesTeamMembers { get; set; }
    TelerikGrid<MainModel> GridRef { get; set; }

    async Task OnRowClickHandler(GridRowClickEventArgs args) {
        // After adding this line, it now requires a double click when the InvokeAsync call uses "await"
         var width = JsInterop.InvokeAsync<int>("getWidth");


        var model = args.Item as MainModel;
        int index = salesTeamMembers.IndexOf(model);
        //todo: you may want to take paging into account for example, or use js interop to get the index of the row based on contents from it like id
        if (index > -1) {
            var state = GridRef.GetState();
            state.ExpandedRows = new List<int> { index };

            await GridRef.SetState(state);
        }

    }


    protected override void OnInitialized() {
        salesTeamMembers = GenerateData();
    }

    private List<MainModel> GenerateData() {
        List<MainModel> data = new List<MainModel>();
        for (int i = 0; i < 5; i++) {
            MainModel mdl = new MainModel { Id = i, Name = $"Name {i}" };
            mdl.Orders = Enumerable.Range(1, 15).Select(x => new DetailsModel { OrderId = x, DealSize = x ^ i }).ToList();
            data.Add(mdl);
        }
        return data;
    }

    public class MainModel {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<DetailsModel> Orders { get; set; }
    }

    public class DetailsModel {
        public int OrderId { get; set; }
        public double DealSize { get; set; }
    }
}

<TelerikGrid Data=@GridData Pageable="true" Height="300px">
    <GridColumns>
        <GridColumn Field="@(nameof(Employee.EmployeeId))">
            <FooterTemplate>
                some footer
            </FooterTemplate>
        </GridColumn>
        <GridColumn Field=@nameof(Employee.Salary) Title="Salary">
        </GridColumn>
        <GridColumn Field=@nameof(Employee.Name)>
        </GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    public List<Employee> GridData { get; set; } // = new List<Employee>(); // workaround

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public decimal Salary { get; set; }
    }
}

Selected value: @selectedValue
<br />

<TelerikComboBox Data="@myComboData"
                 TextField="MyTextField"
                 ValueField="MyValueField"
                 Value="selectedValue"
                 ValueChanged="@((int value) => ValueChangedHandler(value))"
                 Placeholder="Select an item..."
                 ClearButton="true"
                 Enabled="@isEnabled"
                 Filterable="true">
</TelerikComboBox>

@code {
    public bool isEnabled { get; set; } = true;
    IEnumerable<MyDdlModel> myComboData = Enumerable.Range(1, 20).Select(x => new MyDdlModel { MyTextField = "item " + x, MyValueField = x });

    int selectedValue { get; set; } = 3; //usually the current value should come from the model data

    public async Task ValueChangedHandler(int value)
    {
        isEnabled = false;
        await Task.Delay(4000); //simulate network delay

        selectedValue = value;

        isEnabled = true;
    }

    //in a real case, the model is usually in a separate file
    //the model type and value field type must be provided to the dropdpownlist
    public class MyDdlModel
    {
        public int MyValueField { get; set; }
        public string MyTextField { get; set; }
    }
}

<TelerikComboBox Data="@TareTypes" 
                                     TextField="Name" ValueField="Id"
                                     ValueExpression="@(() => Material.TareTypeId)"
                                     ValueChanged="@((int? e) => TareTypeChanged(e))"
                                     Width="200px"
                                     Placeholder="Tare Type" ClearButton="true"></TelerikComboBox>
<TelerikNumericTextBox @bind-Value="@Material.TareWeight" Arrows="false" Enabled="@tareWeightEnabled" ></TelerikNumericTextBox>                      
                    
                    
                    

private void TareTypeChanged(int? tareTypeId)
        {
            Material.TareTypeId = tareTypeId;
            tareWeightEnabled = true;
            if (tareTypeId > 0)
            {
                var tareTypeWeight = TareTypes.Single(t => t.Id == tareTypeId).Weight;
                if (tareTypeWeight.HasValue)
                {
                    Material.TareWeight = tareTypeWeight;
                    tareWeightEnabled = false;
                    editContext.NotifyFieldChanged(editContext.Field("TareWeight"));
                }
            }
        }

<p>Para 1</p><p><br></p><p>Para 2</p><p><br></p><p>Para 3</p>