If you type 15 into the font size combo box and click away, a Javascript error is thrown and the font size of the selected cell does not change. If instead you type 16 and click away, the cell changes correctly. 16 is an option in the drop-down but 15 is not.

Error message:

RadSpreadsheetScripts.js:196 Uncaught TypeError: Cannot read property 'get_text' of null


The font size combo box works correctly in the Kendo spreadsheet demo (both with the current and the 2017.1.124 Kendo version ). You can also press enter to commit your typed font size in the Kendo widget, but not in RadSpreadsheet.

Steps to reproduce:
1. Open https://demos.telerik.com/aspnet-ajax/spreadsheet/examples/overview/defaultcs.aspx
2. Click inside the font -size dropdown
3. Type 15 and click outside the SpreadSheet

Result: A JavaScript error is thrown.

The spreadsheet throws Uncaught ReferenceError: kendo is not defined when you type in a number in the quantity field, then click to the next cell.

I've updated the Telerik library to 2026 Q1 (2026.1.211.462) and noticed a JavaScript error "ReferenceError: kendo is not defined." is thrown on the page where the RadSpreadsheet is located.

The default font size on the client is not saved explicitly on the Excel file, so the Excel defaults take over (11px Calibri), so upon subsequent import all cells will have that font.

Steps to repro:

    go to https://demos.telerik.com/aspnet-ajax/spreadsheet/examples/import-export/defaultcs.aspx 
    export the file
    import the file

Expected: nothing changes

Actual: all cells are 11px Calibri
Workaround: Set a default font when the cell font is null
 
public override void SaveWorkbook(Workbook workbook)
{
    string path = "C:\\path-to-output.xlsx";
     
    for (int i = 0; i < workbook.Sheets.Count; i++)
    {
        for (int j = 0; j < workbook.Sheets[i].Rows.Count; j++)
        {
            for (int l = 0; l < workbook.Sheets[i].Rows[i].Cells.Count; l++)
            {
                string fontFamily = workbook.Sheets[i].Rows[i].Cells[l].FontFamily;
                workbook.Sheets[i].Rows[i].Cells[l].FontFamily = !string.IsNullOrEmpty(fontFamily) ? fontFamily : "Courier New";
 
                double? fontSize = workbook.Sheets[i].Rows[i].Cells[l].FontSize;
                workbook.Sheets[i].Rows[i].Cells[l].FontSize = fontSize.HasValue ? fontSize : 12;
            }
        }
    }
    workbook.Save(path);
}
 

http://screencast.com/t/FJjlN3yw

The error message reads
'ContextMenus' could not be initialized. Details: Object reference on set to an instance of an object.

I have RadSpreadsheet with 5 rows. If I copy 10 rows from Excel into RadSpreadsheet, it will show error message "Cannot paste, because area not the same size".

Is it possible to get RadSpreadsheet to automatically add rows when we paste data? (similar to the Kendo Spreadsheet Widget)

Please add a cell Name field visible on the client and server side. If this name could be grabbed from an excel spreadsheet using the naming functionality built into excel, that would be a major plus.

Repro: 

<telerik:RadSpreadsheet runat="server" ID="RadSpreadsheet1" />
<telerik:RadSpreadsheet runat="server" ID="RadSpreadsheet2" />

protected void Page_Load(object sender, EventArgs e)
{
    var workbook = new Workbook();
    var sheet1 = workbook.AddSheet();

    AddDateRow(sheet1);

    sheet1.Columns = new List<Column>() { new Column() { Index = 1, Width = 150 } };

    RadSpreadsheet1.Sheets.Add(sheet1);
    RadSpreadsheet2.Sheets.Add(sheet1);

    RadSpreadsheet1.ColumnsCount = 5;
    RadSpreadsheet1.RowsCount = 10;
}

private void AddDateRow(Worksheet sheet1)
{
    var row = new Row() { Index = 0 };
    Cell firstCell = new Cell() { Index = 0, Value = "Select Date:", Bold = true };
    row.AddCell(firstCell);

    Cell secondCell = new Cell() { Index = 1, Value = "", Bold = true, Background = "#fef0cd", Format = "mmmm d, yyyy" };

    secondCell.Validation = new Validation()
    {
        AllowNulls = true,
        DataType = "date",
        ShowButton = true,
        ComparerType = "between",
        From = "DATEVALUE(\"1/1/2000\")",
        To = "DATEVALUE(\"12/31/2020\")",
        Type = "reject",
        TitleTemplate = "Invalid date selected",
        MessageTemplate = "Select a date between year 2000 and 2020."
    };

    row.AddCell(secondCell);
    sheet1.AddRow(row);
}

Please can you implement cell-based drag-and-drop in the radSpreadsheet control.

The control looks amazing.

This feature would enable me to completely rewrite and simplify a number of my applications and give them a much more professional look-and-feel.

Regards, Paul.

In Internet Explorer version 11.418.18362.0, when hovering over the lower-right dot the cursor doesn't change to the expected cross-hair. 

To Reproduce:

1. Open IE11

2. Navigate to the ASP.NET Spreadsheet Demo

3. Highlight a few cells

4. Hover the cursor over the lower-right dot

Expected Behavior:

The cursor changes to a thin cross-hair icon but it doesn't change in IE 11.

The Spreadsheet control looks fantastic and will help us replace existing functionality, along with building new streamlined user interfaces.

Please include the ability to specify individual cells that function as drop-downs, where we could bind the data to an external source and have the user select one of the options.

I would like to see the ability to add checkboxes to spreadsheet cells.  In particular, I would like to check boxes in the top row and/or the right column to select rows or columns and then modify cell values based on the the selected checkboxes. 

Can be interesting the power pivot functionality to be supported for spreadsheet control for telerik ui for Ajax.Net.

The spreadsheet adjusts the width based on how many toolbar items are available.  The width property doesn't help. It would be nice to have the spreadsheet list of tools to collapse if a width is specified that is smaller than the toolbar row at the top.  I don't always want the spreadsheet to be the same width as the tools that are available.