Telerik | Combobox update | Add image | Checklist

1. First publish the update, and worked on Telerik exception - Server: .NET framework - 3.5 or 4.5 need upgraded
2. Restored old version
3. Tried again, learned a few things
4. Tried to add a new page to test, and keep DropDownList aspx page working
5. Try to test Combobox example - also failed
6. Windows server 2012 R2 - download .NET framework 4.8 
7. Telerik Combobox upgrade - working