On .Net 6, the System.Json.Text serializer now seems to choke on the return value in the MakeAssertion function.

[abergs]

It throws this exception:
"Serialization and deserialization of 'System.IntPtr' instances are not supported. Path: $.Result.AttestationCertificate.Handle."

The problem can also be recreated in your current master branch if you register a new credential in the demo app under Custom with Direct attestation

Originally posted in #305 #305 (comment)

[abergs]

The root problem is quite self explanatory. System.Json.Text does not support serialization of System.IntPtr.

The CredentialMakeResult contains a X509Certificate2 which contains the System.IntPtr as the Handle property.

There are many ways to solve this problems:

1. Not serialize the X509Certificate2 (e.g. setting AttestationCertificate it to null, before serialization)
2. Convert the entire Result object to a custom DTO that has the properties to are interested in
3. Use a custom converter

Thanks for the report. I have fixed the problem in our Demo site. @m-gug

[dIeGoLi]

Maybe it would make sense to add [JsonIgnore] attribute this property. That way we do not have to set the property to null manually.