Message fields are not nullable and have no proper way to say they have no value about quickfixn HOT 2 CLOSED

Are you new to QuickFIX, by any chance? Your question makes me think you don't have working experience with this engine's C++ or Java predecessors.

To test for field presence, FieldMap (base class of Message) has IsSetField(tag) and IsSetField(IField), and generated Message classes have IsSetXXX() fields for field in the message. You should be using these.

What are you thinking you need to try/catch? You should not be catching FieldNotFound exceptions, for the most part. Those are used by the engine; when an OnMessage() callback throws one, the engine catches it and sends a reject to the counterparty. The assumption here is that you required a field, and the counterparty didn't obey your requirement. (If it was an optional field, you should have checked for it first with one of the IsSet fields.)

I'm inclined to close this Issue, unless you have a further case for it. I don't see it as a bug or as a needed feature.

from quickfixn.

As new as it gets ;) THis is quite a lot about .NET standard behavior, though - I can see cases where the exception gets ugly.

Actually ;) I just confirmed - there areIsSetXXX methods. Sorry. Closing.

from quickfixn.