One of the things to know when you are going to upgrade your Sitecore instance from “8.something” to 9.0.x is that some templates may have been removed/deprecated in Sitecore 9…

An example of this issue are Profile Cards persona template…

In Sitecore 8.2 update 6 we have

and in Sitecore 9 we do not have any longer the Profile Card – Persona

Honestly, I do not think it is not a massive loss for marketers and I consider this simplification a good improvement…

However, in the case, you are migrating a Sitecore instance from 8.x to 9 and you have profile card persona defined, you have to remember to manually change their template to Profile Card to avoid unexpected behaviors…