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Mitigation: PNG Frames in Icon Objects

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Starting with .NET Framework 4.6, the Icon.ToBitmap method successfully converts icons with PNG frames into Bitmap objects.

In apps that target the .NET Framework 4.5.2 and earlier versions, the Icon.ToBitmap method throws an ArgumentOutOfRangeException exception if the Icon object has PNG frames.

Impact

This change affects apps that are recompiled to target the .NET Framework 4.6 and that implement special handling for the ArgumentOutOfRangeException that is thrown when an Icon object has PNG frames. When running under .NET Framework 4.6, the conversion is successful, an ArgumentOutOfRangeException is no longer thrown, and therefore the exception handler is no longer invoked.

Mitigation

If this behavior is undesirable, you can retain the previous behavior by adding the following element to the <runtime> section of your app.config file:

<AppContextSwitchOverrides
      value="Switch.System.Drawing.DontSupportPngFramesInIcons=true" />

If the app.config file already contains the AppContextSwitchOverrides element, the new value should be merged with the value attribute like this:

<AppContextSwitchOverrides
      value="Switch.System.Drawing.DontSupportPngFramesInIcons=true;previous key=previous-value" />

See also