Breaking changes for migration from Version 3.0 Preview 9 to 3.0 RC1

If you're migrating from 3.0 Preview 9 to 3.0 RC1 of .NET Core, review the following topics for breaking changes that may affect your app:

Windows Forms

Change of access for AccessibleObject.RuntimeIDFirstItem

Starting in .NET Core 3.0 RC1, the accessibility of AccessibleObject.RuntimeIDFirstItem has changed from protected to internal.

Change description

Starting with .NET Core 3.0 Preview 4, the AccessibleObject.RuntimeIDFirstItem field was protected. Starting with .NET Core 3.0 RC1, it has changed from protected to internal to align with the accessibility of the field in the .NET Framework.

Version introduced

3.0 RC1

The change can affect you if you've developed a .NET Core app with a type that derives from AccessibleObject and accesses the RuntimeIDFirstItem field. If this is the case, you can define a local constant as follows:

const int RuntimeIDFirstItem = 0x2a;

Category

Windows Forms

Affected APIs

  • Not detectable via API analysis.

Duplicated APIs removed from Windows Forms

A number of APIs accidentally duplicated in the System.Windows.Forms namespace starting in .NET Core 3.0 Preview 4 have been removed in .NET Core 3.0 RC1.

Change description

.NET Core 3.0 Preview 4 inadvertently duplicated a number of types in the System.Windows.Forms namespace that already existed in the System.ComponentModel.Design namespace. Starting with .NET Core 3.0 RC1, these duplicated types are no longer available. The following table shows lists the original type and its duplicated type:

Original type Duplicated type
System.ComponentModel.Design.DesignerActionListsChangedEventArgs System.Windows.Forms.DesignerActionListsChangedEventArgs
System.ComponentModel.Design.DesignerActionListsChangedEventHandler System.Windows.Forms.DesignerActionListsChangedEventHandler
System.ComponentModel.Design.DesignerActionListsChangedType System.Windows.Forms.DesignerActionListsChangedType
System.ComponentModel.Design.DesignerActionUIService System.Windows.Forms.DesignerActionUIService
System.ComponentModel.Design.DesignerCommandSet System.Windows.Forms.DesignerCommandSet

Version introduced

3.0 RC1

Update the code to reference the original type, as shown in the Original type column of the table.

Category

Windows Forms

Affected APIs

  • Not detectable via API analysis.