MFA login flow and reuse-condition

[Cantor, Scott]

That's a subject c14n error, nothing to do with what you're asking about.

One or more of your login flows is producing a Subject that you don't have a suitable c14n flow configured to handle. Either that has to change, or the login flow's behavior around the Principals it's including in the Subject has to change to get a principal name out of it. If all you confgure is "simple", then all the login flows have to populate the Subject with exactly one UsernamePrincipal or it will be unable to handle it.

-- Scott