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Obsolete Windows Forms features in .NET 7+

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Starting in .NET 7, some Windows Forms APIs are marked as obsolete (or otherwise produce a warning) with custom diagnostic IDs of the format WFDEVXXX.

If you encounter build warnings or errors due to usage of an obsolete API, follow the specific guidance provided for the diagnostic ID listed in the Reference section. Warnings or errors for these obsoletions can't be suppressed using the standard diagnostic ID (CS0618) for obsolete types or members; use the custom WFDEVXXX diagnostic ID values instead. For more information, see Suppress warnings.

Reference

The following table provides an index to the WFDEVXXX obsoletions and warnings in .NET 7+.

Diagnostic ID Warning or error Description
WFDEV001 Warning Casting to/from IntPtr is unsafe. Use WParamInternal, LParamInternal, or ResultInternal instead.
WFDEV002 Warning/error System.Windows.Forms.DomainUpDown.DomainUpDownAccessibleObject is no longer used to provide accessible support for DomainUpDown controls. Use AccessibleObject instead.
WFDEV003 Warning System.Windows.Forms.DomainUpDown.DomainItemAccessibleObject is no longer used to provide accessible support for DomainUpDown items. Use AccessibleObject instead.

Suppress warnings

It's recommended that you use an available workaround whenever possible. However, if you cannot change your code, you can suppress warnings through a #pragma directive or a <NoWarn> project setting. If you must use the obsolete APIs and the WFDEVXXX diagnostic does not surface as an error, you can suppress the warning in code or in your project file.

To suppress the warnings in code:

// Disable the warning.
#pragma warning disable WFDEV001

// Code that uses obsolete API.
//...

// Re-enable the warning.
#pragma warning restore WFDEV001

To suppress the warnings in a project file:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
   <TargetFramework>net7.0</TargetFramework>
   <!-- NoWarn below suppresses WFDEV001 project-wide -->
   <NoWarn>$(NoWarn);WFDEV001</NoWarn>
   <!-- To suppress multiple warnings, you can use multiple NoWarn elements -->
   <NoWarn>$(NoWarn);WFDEV001</NoWarn>
   <NoWarn>$(NoWarn);WFDEV003</NoWarn>
   <!-- Alternatively, you can suppress multiple warnings by using a semicolon-delimited list -->
   <NoWarn>$(NoWarn);WFDEV001;WFDEV003</NoWarn>
  </PropertyGroup>
</Project>

Note

Suppressing warnings in this way only disables the obsoletion warnings you specify. It doesn't disable any other warnings, including obsoletion warnings with different diagnostic IDs.

See also