(Case 1103421) Upgrading a project doesn't upgrade TextMeshPro prefabs

I upgrading my project from Unity 2018.1.0f2 that was using TextMeshPro 2017.3-1.0.56

I got lots of errors in the console after upgrading, but found this article that told me how to fix it: https://forum.unity.com/threads/tex...migration-to-package-manager-releases.511748/

However, it only 'fixed' TextMeshPro GOs that were in scenes. It missed all my prefabs and they remained broken as the TextMeshPro component now said 'Script Missing'.

To fix the problem, I had to upgrade TextMeshPro using the Package Manager (to version 1.3.0) BEFORE I upgraded Unity. Then Upgrading Unity worked fine.

Not sure if that is some kind of requirement or not, and also would be good if all the info in that post I found was included automatically in the Unity upgrade, or at least tell me about it and point me in a direction on how to fix things.

I've created a simple test case and uploaded with the case: 1103421