I am upgrading from 5.1.6 to 5.2-latest, and I encounter the following issue.
ImportError: No module named contentmigration.basemigrator.migrator
This is because the plone.app.contenttypes dexterity migrator depends on Archetypes, but Plone 5.2 doesn't ship with it any more. I have read through the below items, but I wanted to be sure that I understood the resolution correctly. It didn't seem to have a 100% complete solution that I could tell, but forum posts do present some potential working solutions.
During an earlier migration from Plone 4.3 to Plone 5.0.6, I have already migrated from Archetypes to Dexterity. If I read the steps properly in the posts which I mention above, it says to roll back from 5.2 to 5.1 so that I can run the GenericSetup uninstall profile for Products.ATContentTypes. Then I should be able to resume the move from 5.1 to 5.2.
If anybody could verify that, I would appreciate it greatly. Thank you!