Ah, I see. The issue is that BinaryFormatter's constructor still works, so my feeble attempt to catch an exception there will not work.

@lostmsu Suggestions?

• Should we just switch to the NoopFormatter by default?
• Should we default to "non-recoverable" in Shutdown and provide a new method to "shutdown with stashing"?

@filmor can't we detect that we are running on .NET Framework/Mono and use BinaryFormatter, otherwise use noo?

True, that's probably the quick-fix. On the other hand, since this is such an uncommon scenario, wouldn't it make sense to adjust the defaults to also get "quicker" shutdown unless one explicitly chooses otherwise?

I'm OK in the future, but right now it would be a breaking change for anyone who happens to use it with Unity.

So, to clarify, is this blocking us from moving to .net 9?

I can also confirm that this issue happens using dotnet 9. The workaround to surround the shutdown method in a try catch statement works so far. Not using the shtutdown method causes that the process endlessly hangs, so it's required even if it throws the exception above.

It would be great if this issue could be fixed. It's not a show-stopper (if you aware of this issue), but it's definitely not elegant.

It's possible to create your own 'NullFormatter' as a replacement, I've tested this using NET 9.0 and the most recent NuGet release of Python.NET (3.0.5) and it didn't cause any issues yet. This is probably not a good idea, so use on your own risk. Out of all possible solutions, I felt like this is the 'cleanest' one. 😅

#pragma warning disable SYSLIB0011
public class NullFormatter : IFormatter
#pragma warning restore SYSLIB0011
{
    public SerializationBinder Binder { get; set; }
    public StreamingContext Context { get; set; }
    #pragma warning disable SYSLIB0050
    public ISurrogateSelector SurrogateSelector { get; set; }
    #pragma warning restore SYSLIB0050

    public object Deserialize(Stream serializationStream)
    {
        return null;
    }

    public void Serialize(Stream serializationStream, object graph)
    {
        // ...
    }
}