DCE ships a bunch of upgrade wizards with, to upgrade from older releases of DCE:
This update checks all DCE field variables for being valid. If not it can correct them automatically.
In a very old version of DCE (0.x) the relations between DCE fields and DCEs were m:n. This wizard helps to migrate old MM relations.
Do not delete the old MM tables, before you have performed this upgrade wizard. Database compare offers you to delete the tables, what you can do, afterwards.
In the past DCE named tabs in FlexForm configuration like this:
But this has the effect that all your data is broken, when you change the order of tabs in a DCE. Now the sheets have a named identifier. You can set the identifier in the variable field which is also visible for tab fields, now.
The FlexForm configuration looks like this now:
The very first sheet has the identifier/variable “tabGeneral” by default. This wizard takes are about this.