CA1416 This call site is reachable on all platforms. 'Image.FromStream(Stream)' is only supported on: 'windows'

Question

Upgrading NuGet System.Drawing.Common to 6.0.0 causes the following error:

CA1416 This call site is reachable on all platforms. 'Image.FromStream(Stream)' is only supported on: 'windows'.

https://www.nuget.org/packages/System.Drawing.Common/

The affected code is the following:

var drawingImage = System.Drawing.Image.FromStream(memstr);

We use the library to access the method GetThumbnailImage .

public byte[] GetThumbnailBytes(byte[] imageBytes)
{
    var thumbnailBytes = Array.Empty<byte>();

    using (MemoryStream memstr = new MemoryStream(imageBytes))
    {
        var drawingImage = System.Drawing.Image.FromStream(memstr);
        var thumbnailSize = GetThumbnailSize(drawingImage);

        var thumbnail = drawingImage.GetThumbnailImage(thumbnailSize.Width, thumbnailSize.Height, null, IntPtr.Zero);

        var ms = thumbnail.ToStream(drawingImage.RawFormat);

        thumbnailBytes = ms.ReadFully();
    }

    return thumbnailBytes;
}

We only host the application on Azure so targeting Windows is fine but replacing GetThumbnailImage is acceptable as well.

Answer 1

Reading about the breaking change on Microsoft Docs and that we only target the Windows platform I decided to do the quickest path to victory for the moment and set Target OS to Windows .

But this code won't warn if the project targets Windows

https://docs.microsoft.com/en-us/dotnet/core/compatibility/code-analysis/5.0/ca1416-platform-compatibility-analyzer

Answer 2

This has been an long open issue

I have got around it by editing my shared assembly info (not autogenerated) with

#if NET6_0
[assembly: System.Runtime.Versioning.SupportedOSPlatform("windows7.0")]
#endif