FileNotFoundException Thrown in RadPdfViewer when PDF Document gets Loaded

Updated on Nov 21, 2025

Environment

Product	RadPdfViewer for WPF
Version	2025.4.1111

Description

FileNotFoundException is thrown when a document is loaded in RadPdfViewer (often at startup of the app). The error occurs only with some documents and only when the application is published as self-contained app. It doesn't occur during debug or release configurations, until the app is published.

The file that cannot be found is the System.Drawing.Common.dll which is used in the Telerik.Windows.Documents.Core.Fonts.SystemFontsManager.IsMonospaced static method.

The exception trace is the following:

stacktrace

 at Telerik.Windows.Documents.Core.Fonts.SystemFontsManager.IsMonospaced(String fontFamily)
   at Telerik.Windows.Documents.Core.Fonts.FontProperties..ctor(FontFamily fontFamily, FontStyle fontStyle, FontWeight fontWeight)
   at Telerik.Windows.Documents.Fixed.Utilities.Rendering.TextRenderingContext..ctor(TextFragment textFragment, Rect currentContainerBounds, IContentRenderingContext parentContext)
   at Telerik.Windows.Documents.Fixed.Utilities.Rendering.Helpers.TextRenderingHelper.RenderTextFragment(IFixedContentRenderer renderer, TextFragment textFragment, Rect currentContainerBounds, ITextPropertiesOwner textProperties, IContentRenderingContext parentContext)
   at Telerik.Windows.Documents.Fixed.Utilities.Rendering.ContentRootRenderingHelper.RenderContentElement(IFixedContentRenderer renderer, Rect viewport, ContentElementBase element, IContentRenderingContext parentContext)
   at Telerik.Windows.Documents.Fixed.Utilities.Rendering.ContentRootRenderingHelper.RenderContentElementHierarchy(IFixedContentRenderer renderer, Rect viewport, ContentElementsGraph contentElementsGraph, ContentElementBase parent, IContentRenderingContext parentContext)
   at Telerik.Windows.Documents.Fixed.Utilities.Rendering.ContentRootRenderingHelper.RenderContentElements(IFixedContentRenderer renderer, Rect viewport, IContentRootElement element, Rect elementBounds, IContentRenderingContext parentContext)
   at Telerik.Windows.Documents.Fixed.Utilities.Rendering.FixedPageContentRenderingHelper.RenderContentElements(IFixedContentRenderer renderer, Rect viewport)
   at Telerik.Windows.Documents.Fixed.UI.ParallelContentElementsPainter.DrawContentElements(Rect lastViewport)
   at Telerik.Windows.Documents.Fixed.UI.ContentElementsCanvas.PrepareVisuals(Int32 pageNumber)
   at Telerik.Windows.Documents.Fixed.UI.ContentElementsCanvas.RenderAsync(Int32 pageNumber)
   at Telerik.Windows.Documents.Fixed.UI.ContentElementsCanvas.RenderAsync()
   at Telerik.Windows.Documents.Fixed.UI.ContentElementsCanvas.OnRender(DrawingContext dc)

Solution

This happens because the System.Drawing.Common.dll is not automatically copied to the \publish folder by the Visual Studio tooling.

To work this around, you can add a framework reference that points to Microsoft.WindowsDesktop.App in the .csproj file of the project.

xml

   <ItemGroup>
       <FrameworkReference Include="Microsoft.WindowsDesktop.App" />
   </ItemGroup>