Cannot access Freezable System.Windows.Media.SolidColorBrush across threads because it cannot be frozen

Updated on Sep 15, 2025

Environment

Product	Version
Telerik UI for WPF	2023.3.1114

Description

InvalidOperationException occurs in some cases when using the Telerik Windows8 theme in a scenario with multiple UI threads.

InvalidOperationException was unhandled by user code Message=Cannot access Freezable 'System.Windows.Media.SolidColorBrush' across threads because it cannot be frozen.

Solution

To fix the issue, call the Freeze method on the Windows8Palette object.

C#

	Telerik.Windows.Controls.Windows8Palette.Palette.Freeze();