Read the documentation for CancelationTokenSource.CancelAfter:

this method will throw an ArgumentOutOfRangeException when: delay.TotalMilliseconds is less than -1 or greater than Int32.MaxValue (or UInt32.MaxValue - 1 on some versions of .NET). Note that this upper bound is more restrictive than TimeSpan.MaxValue.

----------------------------------------------------

your code in CancelationTokenSourceFactory.CreateTokenSource does this check:

if (timeSpan.HasValue && timeSpan.Value != TimeSpan.MaxValue)

this check for TimeSpan.MaxValue seems totally pointless here, if timeSpan is anything between ~2147483647 and 922337203685476 milliseconds long this will still just throw a ArgumentOutOfRangeException.

I suspect that this check was intended as a way to prevent creating a cancellation timer that never triggers in the CancellationTokenSource, which should look like this:

if (timeSpan.HasValue && timeSpan != Timeout.InfiniteTimeSpan) //Timeout.InfiniteTimeSpan is -1 milliseconds

In the 2025 version of the Documents packages, "TimeSpan? timeout" were added to a number of interfaces, with the old versions obsoleted, for example: IWorkbookFormatProvider.Import & IWorkbookFormatProvider.Export.

This is a very strange choice, because this limits the flexibility of the interfaces for no reason at all. By only providing the TimeSpan parameter and not a CancellationToken is currently impossible to cancel the operation because e.g. an API request was canceled.

Internally these methods are implemented by first creating a cancellation token using

using CancellationTokenSource cancellationTokenSource = CancelationTokenSourceFactory.CreateTokenSource(timeout);

the token from this CancellationTokenSource is then passed to a protected method. Because this internal method uses a CancellationToken anyway, there is practically 0 development cost to exposing this in the interface, which makes the choice not to do so even more confusing.

The interfaces should expose methods that take a CancellationToken instead of a TimeSpan. This would allow for the same functionality as the TimeSpan parameter, by simply passing a cancellation token with a CancelAfter set with a TimeSpan, and an extension method could be provided for the interface which does exactly that, so users can still call these methods with a TimeSpan parameter if they wish to do so for convenience.

Please, in the next version, make these interfaces methods like this:

Workbook Import(Stream input, CancellationToken cancellationToken = default);
void Export(Workbook workbook, Stream output, CancellationToken cancellationToken = default);

and, for convenience, add extension methods for these like this:

public static class WorkbookFormatProviderExtensions
{
    public static Workbook Import(this IWorkbookFormatProvider workbookFormatProvider, Stream input, TimeSpan? timeout)
    {
        using CancellationTokenSource cancellationTokenSource = CancelationTokenSourceFactory.CreateTokenSource(timeout);
        return workbookFormatProvider.Import(input, cancellationTokenSource.Token);
    }
}

Affected interfaces I've run into so far:

• Telerik.Windows.Documents.Spreadsheet.FormatProviders.IWorkbookFormatProvider
• Telerik.Windows.Documents.Common.FormatProviders.IFormatProvider<T>

There may be more with this same pattern, I haven't checked.

After Excel introduced the dynamic array support, files produced with the older Excel versions have formulas that may be displayed with @ in some contexts. For example a file that had the following:

=SUM(IF(A1:A10=1, B1:B10, 0))

Will be displayed like so:

=SUM(IF(@A1:A10=1, B1:B10, 0))

This is done in order to preserve the behavior of the files created in older versions of Excel.

The files created by SpreadProcessing are also treated by Excel as if they are created by pre-dynamic array Excel. Please, introduce support for the new behavior.

Workaround: this is the missing part after the export:

MS Excel offers the following text styling options:

When importing a document containing a Plain Text SDT with multiple paragraphs an exception is thrown:

Telerik.Windows.Documents.Flow.Model.Annotations.StructuredDocumentTags.Builders.SdtBuilderFailureException: "This content control type cannot be inserted around multiple paragraphs."

If a worksheet has page breaks, but Fit to pages is also set to true, the page breaks should not be respected.

wb.ActiveWorksheet.WorksheetPageSetup.PageBreaks.Clear();

An exception is thrown when the file contains the following format string 

"      PE @ "??0.0;-"      PE @ "??0.0;"      PE @   New";"      PE @ "_0_0@

The exception is thrown in the ValidateNumberFormatDescriptors method.

In excel, if you set word wrap to cell content, make the column wider and then autofit the column in which it is, the content will fit to a reasonable width, as seen in the image below.

When doing the same in SpreadProcessing, the result is always a narrow column:

            CellSelection cellSelection = sheet.Cells[0, 0];
            cellSelection.SetIsWrapped(true);

            ColumnSelection columnSelection = sheet.Columns[0];
            columnSelection.SetWidth(new ColumnWidth(100, true));
            columnSelection.AutoFitWidth();

Result:

Here are the same steps performed in WPF RadSpreadsheet, which uses RadSpreadProcessing for its engine: