You CustomUserProvisioning microflow did not return a LoginFeedback object where LoginAllowed=true.
The CustomUserProvisioning is custom, so i suggest doing some debugging there.
I hope this helps.
Did you already found the issue?
I had the same error message and we found out that it was an issue on our AD/SAML setup. The used principalname was for some users in Lowercase and some in Uppercase.
So now we have ToLowercase (user.userprincipalname) and we don’t get the error message anymore.
We also had the same error message. We first used the entity Account for the login processs and changed it afterwards to the entity Gebruiker that is a specialization of Account. The error disappeared after deleting all the accounts created with the former login entity Account. The reason behind this is that Mendix now wanted to create an entity Gebruiker and thus also for Account that already existed.