To reproduce: 1. Create a project 2. Add a Telerik form 3. Add a RadCommandBar 4. Add some buttons 5. Debug application (forget you are running application) 6. Click on add button on command bar. As a result, Visual studio Crashes. Note: if you perform the same steps with RadRibbonBar a message is shown that the file can't be modified while debugging. Please refer to the attached screenshot.