From .Net Framework 4.7.2 to .Net Core 3

I made a WinForm desktop application, written in VB.Net, which is currently running under Framework 4.7.2. It has more than twelve libraries also in VB.Net.

I want to study its deployment on MAC. To do this, at first, so I have to go under .Net Core 3.
I installed and ran the port analyzer on this application. The displayed compatibility of the app and its libraries is greater than 90%. 100% for a library.

I use VS 2019 Community, last updated, with the WinForm designer installed but I do not yet master the conversion mechanisms and I currently have difficulties to interpret detailed reports that do not provide sufficient information to allow me to make the necessary corrections to the code. For example :
Target type: T: System.Windows.Forms.FormBorderStyle
Target member: T: System.Windows.Forms.FormBorderStyle
.NET Core + Platform Extension: Supported 3.0+
.NET Core: Not supported
.NET Standard + Platform Extensions: Not supported
Recommended changes: empty

Is there a tool that automates, at least in part, the conversion of code to .Net Core?
Thank you for your help.

WinForms are not supported on macOS, even though most other parts of .Net Core 3.0 are, so I think what you’re attempting to do doesn’t make sense.

Thank You svick,
WPF is not portable on MacOS, WinForm no advantage. This means that you have to rebuild a new IHM on Mac and only have some libraries converted to .Net Standard? Are there tools to do this?

Windows Forms and WPF in .NET Core 3 is more to support .NET Core in Windows Forms and WPF applications than supporting Windows Forms and WPF in all .NET Core supported runtimes.

Windows Forms and WPF are Windows technologies and nothing changed there.

Are there tools for converting a .NET Framework application or library to .NET Core 3?

There’s dotnet try-convert but, as the name says, it tries.

I loaded **

** and I compiled it with Visual Studio.
So I get an executable.
I open a command window on the directory of this executable:
1- The try-convert command prints the syntax of the app. Okay.
2- I try to start the conversion of a small framework project but I am not used to the command lines and I can not find the good writing as you can see on the attached image.

Can you help me on this command?
Thank you

The first thing I would suggest will be to upgrade your project to sdk project format.

You can use a tool like

I also recommend using the preview versions of VS because the designer is still experimental

After you get your project compiling on a .net framework sdk project switch to a .net core winforms project and compile and compare the error list

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