Windows Forms obsoletions and warnings (.NET 7)
Some Windows Forms APIs have been marked as obsolete, starting in .NET 7. Other APIs aren't obsolete but will cause a compile-time warning if you reference them.
Previous behavior
In previous .NET versions, these APIs can be used without any build warning.
New behavior
In .NET 7 and later versions, use of these APIs produces a compile-time warning or error with a custom diagnostic ID. The use of custom diagnostic IDs allows you to suppress the warnings individually instead of blanket-suppressing all obsoletion warnings.
The following table lists the custom diagnostic IDs and their corresponding warning messages.
| Diagnostic ID | Description | Severity | Version introduced |
|---|---|---|---|
| WFDEV001 | Casting to/from IntPtr is unsafe. Use WParamInternal, LParamInternal, or ResultInternal instead. |
Warning | Preview 1 |
| WFDEV002 | System.Windows.Forms.DomainUpDown.DomainUpDownAccessibleObject is no longer used to provide accessible support for DomainUpDown controls. Use AccessibleObject instead. | Warning | RC 1 |
| WFDEV003 | System.Windows.Forms.DomainUpDown.DomainItemAccessibleObject is no longer used to provide accessible support for DomainUpDown items. Use AccessibleObject instead. | Warning | RC 1 |
Version introduced
.NET 7
Type of breaking change
These obsoletions and warnings can affect source compatibility.
Recommended action
- Follow the specific guidance provided for the each diagnostic ID using the URL link provided on the warning.
- If necessary, you can suppress the warning using the custom
WFDEVxxxdiagnostic ID value.
Affected APIs
WFDEV001
- System.Windows.Forms.Message.WParam
- System.Windows.Forms.Message.LParam
- System.Windows.Forms.Message.Result
WFDEV002
WFDEV003
See also
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