Worked great for me

I build and maintain small business websites for a living and I recently had a client that wanted to change themes. We were using The7 by ThemeForest, and are changing to Divi by Elegant Themes. The7 had several built-in custom post types that we were using, but of course when I changed the theme the content was simply inaccessible. I found this plugin to be a good solution.

I had to reactivate the old theme so that the custom post types were re-registered, then I converted them to normal Posts. The category assignment feature didn’t work as I thought it would, but I batch assigned a temporary category to all of the posts I was converting.

Then I changed themes to the new one, and used the plugin again to convert all posts in the temporary category to a new custom post type in the Divi theme.

This worked great for me, but it’s pretty simplistic and may not work as well in everyone’s case. This plugin saved me a ton of time not having to rebuild those post items.