Telerik.Reporting (ReportPackager) complains about Telerik.Reporting.Data.Design, Version=19.0.25.211

[Brendon]

We are using 19.0.25.211 of the report viewer (we cannot go higher due to other constraints)

When using Telerik.Reporting.ReportPackager to Unpack an existing report file, we get the following error.

Could not load file or assembly 'Telerik.Reporting.Data.Design, Version=19.0.25.211

I cannot find detail on this specific assembly anywhere.

We need to Unpack the report in order to update internal datasources etc.

[Ivet]

Hi Brendon,

Thank you for reaching out.

There is no public assembly named Telerik.Reporting.Data.Design, so the “Could not load file or assembly" error usually means your process is trying to resolve a design‑time dependency that isn’t meant (or needed) at runtime, often because of a version mismatch, stale GAC entry, or a probing path issue.

The WPF Report Viewer is built with Telerik UI for WPF components, hence requires the corresponding DLLs or NuGet packages to be referenced in the project hosting the viewer.

All the required assemblies/packages are listed in the article section Steps to add report viewer to a WPF .NET 8+ project.

You may reference the Telerik Windows packages instead of the DLLs.  Ensure you have correctly configured the Progress Telerik source: Adding the Telerik NuGet Feed to Your System.

Note that there are more Telerik WPF assemblies/packages needed for a fully working WPF Report Viewer. Here is the list for clarity:

Telerik.Windows.Controls (No XAML)
Telerik.Windows.Controls.Input (No XAML)
Telerik.Windows.Controls.Navigation (No XAML)
Telerik.Windows.Controls.ConversationalUI (No XAML)
Telerik.Windows.Data (No XAML)

You may reference them as NuGet packages or DLLs.

To better assist you in resolving this issue, could you please send me the project that throws this error so I can test it locally? It would also be very helpful if you could provide me with the Тrace log.

• Trace log for .Net - How to troubleshoot errors in ASP.NET Core projects - Telerik Reporting
• Trace log for .Net Framework - How to: Create and Initialize Trace Listeners - .NET Framework | Microsoft Learn

If you are hesitant to send your project here, you can open a ticket and provide the details there.

Looking forward to your next reply.

Regards,
Ivet
Progress Telerik