This can also happen if your previous version has not changed, but you have several xcdatamodel files and load them using mergedModelFromBundles: This is how MagicalRecord loads your model files.
So, if you have a dependency (possibly on your containers) that has a different xcdatamodel, then your actual source data model will not be the same as the one you are transitioning with, since the source data model is a unified model of everything from for mergedModelFromBundles:
To solve this problem, you will need to create a simple version that matches what is stored, and not just in the previous version. To do this, add the missing models to the source data model you are switching from, and you will get these models from another xcdatamodel . Fortunately, you can simply copy and paste all models by selecting them from the list of objects.
For instance:
To: (Fails)
Main.xcdatamodel Version 2: Users, Posts, Comments Version 1: Users, Posts Other.xcdatamodel Version 1: Events, Data
After:
Main.xcdatamodel Version 2: Users, Posts, Comments Version 1: Users, Posts, Events, Data Other.xcdatamodel Version 1: Events, Data
Saved Data Model:
Version 1: Users, Posts, Events, Data Version 2: Users, Posts, Comments, Events, Data