diagnostic:  The e-File database indicates that Form 8962 or a binary attachment with description containing "ACA Explanation" must be present in the attachment with description containing "ACA Explanation" must be present in the filing.

I'm hoping for a workaround to this diagnostic so that I can e-file.

What is a "binary attachment"?

It suggests that an attachment can be sent (with 8453?). What would I attach and what input is needed (on Form 4.4)?