Environment:

• Visual Studio 2026 Version 18.6.1 (May 2026 release)
• Visual Studio language: Japanese
• .NET 10 WPF project
• Telerik UI for WPF 2026.2.520
  

Problem:

Visual Studio freezes frequently while editing XAML when using Telerik UI for WPF 2026.2.520.
The issue does NOT occur with Telerik UI for WPF 2026.1.415.

Steps to reproduce:

1. Install the "Progress Telerik UI for WPF Extension"
2. Create a new WPF project using the Telerik extension/template (Empty)
3. Open the automatically generated MainWindow.xaml
4. Inside the existing <Grid> element, type:
   <Grid
5. At the moment XAML IntelliSense/code completion is triggered, Visual Studio freezes

Additional information:

• XAML Designer is disabled
• Deleting the .vs folder does not help
• No third-party Visual Studio extensions are installed
• The issue only occurs with Telerik UI for WPF 2026.2.520
• Downgrading to Telerik UI for WPF 2026.1.415 resolves the issue completely
  

Could you please confirm whether this is a known issue related to Visual Studio 2026 / .NET 10 compatibility?

In the WPF Create New Project Wizard, the target framework versions dropdown is empty when no distribution is installed:

 

Upgrade Wizard for WPF and WinForms doesn't support .NET 10

An error occurred while running the wizard.

Error executing custom action Telerik.Windows.WPF.VSX.Actions.UpdateReferencesAction: System.Runtime.InteropServices.COMException (0x80004005): This reference cannot be removed from the project because it is always referenced by the compiler.
   at VSLangProj.Reference.Remove()
   at Telerik.VSX.Internal.ProjectManagement.ApplicationProjectAssemblyReference.RemoveReference()
   at Telerik.VSX.ProjectConfigurators.ApplicationReferenceManager.RemoveReferences()
   at Telerik.VSX.ProjectConfigurators.ApplicationReferenceManager.UpdateReferences()
   at Telerik.VSX.Actions.UpdateReferencesAction.UpdateReferences(IProjectWrapUIComponents projectWrap)
   at Telerik.VSX.Actions.UpdateReferencesAction.Execute(WizardContext wizardContext, IPropertyDataDictionary arguments, IProjectWrap project)
   at Telerik.VSX.Actions.ProjectActionBase.Execute(WizardContext wizardContext, IPropertyDataDictionary arguments)
   at Telerik.VSX.WizardEngine.Actions.ActionBase.Telerik.WizardFramework.IAction.Execute(IWizardContext wizardContext, IPropertyDataDictionary arguments)
   at Telerik.VSX.WizardEngine.ActionManager.ExecActions()

After installing the WPF software I was not able to open any project in VS 2017 without it hanging.

 

In the end I removed the VS integration and was able to resume development.

 

It was the only Telerik component I had installed. I can't find the version number but it was the latest of the website as of 17th Oct 2019.

 

Can you explain why this happened?