1. Create clean WinForms .NET Framework project.
2. Add Telerik UI for WinForms 2026.2.520.462.
3. Create BaseForm : RadForm.
4. Add RadStatusStrip to BaseForm.
5. Create inherited form RadForm1 : BaseForm.
6. Open inherited form in Visual Studio designer.
7. Designer crashes with NullReferenceException in Telerik.WinControls.UI.Design.RadControlDesigner.OnSetCursor.
8. Remove/comment RadStatusStrip from BaseForm.Designer.cs.
9. Designer opens successfully.

Sample project attached.

 

On 125% dpi:

 However, if you close the list and open it again, the list has the correct height (the gap is gone).

Use attached to reproduce.

Hi, I would like to use the conversion tool to convert a WinForms project to Telerik controls. Unfortunately the menu item is not showing up for me. See attached screenshot. 

The project to be converted does include a reference to System.Windows.Forms. I am using VS2019 with the latest Telerik Winforms release. 

Thanks,

-Lou

Introduce a Converter tool standalone application which does not depend on a specific Visual Studio version.

After a project, built with the standard MS controls, is successfully converted to a Telerik WinForms project, the subscriptions to certain events available in the Designer.cs file may disappear if you open the design view and make some changes. A solution for this behavior is described in the How to Deal with Disappearing Event Handlers after Opening the Designer for a Converted WinForms Project KB Article.

 

Workaround: 
The vsdiffmerge.exe merge tool in Visual Studio 2017 is usually located here: C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\CommonExtensions\Microsoft\TeamFoundation\Team Explorer. You will need to create one additional folder named Ide inside the Team Explorer folder Then you can copy the vsdiffmerge.exe file from the Team Explorer folder to the newly created Ide folder. You can check the attached vsdiffmerge-path.png screenshot.

Then you can create the environment variable like this:
Variable name: VS120COMNTOOLS
Path: C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\CommonExtensions\Microsoft\TeamFoundation\Team Explorer\IDE

   

VS 2022 17.5.1 successfully converts a blank WinForms project without any Telerik control in it.

VS 2022 17.6.2  hangs:

1. Create Windows Forms App
2. Select Target Framework .NET Core 3.1, 5.0 or 6.0
3. Convert to Telerik Controls via the WinForms Extensions menu

You will see that you cannot select version .NET Core 3.1, 5.0 or 6.0 from the drop-down.

If you attempt to convert the project by selecting version 2.0 or 4.0 the Visual Studio will crash.

When we set a checkbox with the CheckState to Indeterminate, then it's serialized by the designer is that order (because VS serialized in alphabetical order).
But next time we open the form, it's unchecked, because setting to Indeterminate before setting IsThreeState to true is ignored.

An exception is thrown when loading a document:

FileNotFoundException: Could not load file or assembly 'Microsoft.Web.WebView2.WinForms, Version=1.0.3719.77, Culture=neutral, PublicKeyToken=2a8ab48044d2601e' or one of its dependencies. The system cannot find the file specified.

In this particular scenario, we have 2 monitors. One with 100 % and one with 150% DPI. When the ScreenTip is shown in 100%, its size is correct. Then if we move the Form to the second monitor that is 150%, the screenTip size is not scaled when shown for the first time. We need to move the mouse to hide and show it again. The second time, the size is correct.

When an appointment has a very short duration (seconds-level, e.g., 1 second and 0 minutes), it does not appear in the RadPrintPreviewDialog. The appointment is visible in the scheduler UI but missing from the print preview.

For example:

Dim ap1 As New Appointment
ap1.Start = New Date(Date.Today.Year, Date.Today.Month, Date.Today.Day, 15, 0, 0)
ap1.End = New Date(Date.Today.Year, Date.Today.Month, Date.Today.Day, 15, 0, 1)
ap1.Description = "not printed"
ap1.Summary = "not printed"
RadScheduler1.Appointments.Add(ap1)

Incorrect calculation of indentation when a paragraph in a list has applied tab space during PDF export.

The AccessibleName property is not respected by the Windows Narrator.

Clients with perpetual license may observe the following warning when using UI.for.WinForms.AllControls.Net90 (v.2026.1.415): 

Telerik and Kendo UI Licensing warning TKL403: Services associated with Telerik Document Processing Libraries version 2026.1.402.80 require a subscription or trial license. Please obtain a subscription license at https://prgress.co/3PwQMKZ

Telerik and Kendo UI Licensing warning TKL004: Unable to locate licenses for all products.

 

************** Exception Text **************
System.InvalidOperationException: Invoke or BeginInvoke cannot be called on a control until the window handle has been created.
   at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
   at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
   at System.Windows.Forms.Control.Invoke(Delegate method)
   at Telerik.WinControls.UIAutomation.RadControlBaseRootUIAutomationProvider`1.get_BoundingRectangle()
   at Telerik.WinControls.UIAutomation.Window.RadFormUIAutomationProvider.Form_Resize(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnResize(EventArgs e)
   at System.Windows.Forms.Form.OnResize(EventArgs e)
   at System.Windows.Forms.Control.OnSizeChanged(EventArgs e)
   at System.Windows.Forms.Control.UpdateBounds(Int32 x, Int32 y, Int32 width, Int32 height, Int32 clientWidth, Int32 clientHeight)
   at System.Windows.Forms.Control.UpdateBounds(Int32 x, Int32 y, Int32 width, Int32 height)
   at System.Windows.Forms.Control.SetBoundsCore(Int32 x, Int32 y, Int32 width, Int32 height, BoundsSpecified specified)
   at System.Windows.Forms.Form.SetBoundsCore(Int32 x, Int32 y, Int32 width, Int32 height, BoundsSpecified specified)
   at Telerik.WinControls.UI.RadFormControlBase.SetBoundsCore(Int32 x, Int32 y, Int32 width, Int32 height, BoundsSpecified specified)
   at System.Windows.Forms.Control.SetBounds(Int32 x, Int32 y, Int32 width, Int32 height, BoundsSpecified specified)
   at System.Windows.Forms.Control.set_Size(Size value)
   at Telerik.WinControls.RadMessageBoxForm.SetSizeAndLocations()
   at Telerik.WinControls.RadMessageBoxForm.SetLabelTextAndSize(String text)
   at Telerik.WinControls.RadMessageBoxForm.set_MessageText(String value)
   at Telerik.WinControls.RadMessageBox.ShowCore(IWin32Window owner, String text, String caption, MessageBoxButtons buttons, Bitmap icon, MessageBoxDefaultButton defaultButton, RightToLeft rightToLeft, String detailsText)
   at dummyReader.FormMain.radButtonLogin_Click(Object sender, EventArgs e)
   at System.EventHandler.Invoke(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at Telerik.WinControls.RadControl.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonBase.buttonElement_Click(Object sender, EventArgs e)
   at Telerik.WinControls.RadElement.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonItem.OnClick(EventArgs e)
   at Telerik.WinControls.UI.RadButtonElement.OnClick(EventArgs e)
   at Telerik.WinControls.RadElement.DoClick(EventArgs e)
   at Telerik.WinControls.RadElement.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadItem.RaiseBubbleEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.RaiseRoutedEvent(RadElement sender, RoutedEventArgs args)
   at Telerik.WinControls.RadElement.DoMouseUp(MouseEventArgs e)
   at Telerik.WinControls.ComponentInputBehavior.OnMouseUp(MouseEventArgs e)
   at Telerik.WinControls.RadControl.OnMouseUp(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at Telerik.WinControls.RadControl.WndProc(Message& m)
   at Telerik.WinControls.UI.RadButton.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)