IndexOutOfRangeException in XamlFormatProvider.Export when exporting RadDocument concurrently

[Zafeer]

Hi Team,

We are encountering an intermittent IndexOutOfRangeException when calling XamlFormatProvider.Export() on a RadDocument.

Exception stack:

System.IndexOutOfRangeException
 at System.Collections.Generic.Dictionary`2.Insert
 at Telerik.Windows.Documents.FormatProviders.Xaml.XamlWriter.TryGetTypeConverter
 at Telerik.Windows.Documents.FormatProviders.Xaml.XamlFormatProvider.Export(RadDocument)

Code:

private string ReadDocumentText(RadDocument document)
{
    if (document == null) return string.Empty;
    return new XamlFormatProvider().Export(document);
}

Notes:

• document is not null

• Each document is different

• Same code works for most documents

• The exception occurs inside Telerik export logic

• Documents are exported concurrently (parallel processing)

• No custom type converters or custom styles added explicitly

Questions:

• Is XamlFormatProvider.Export() thread-safe when used concurrently?

• Can concurrent exports cause internal state corruption (e.g. type converter dictionary)?

• Is there a recommended approach for exporting RadDocument in parallel (e.g. synchronization or per-thread isolation)?

Any guidance would be appreciated.

Thanks.
Zafeer