The biggest change to look out for and that will take some manual work – sorry 😬– is alignment. With the upgrade to Bootstrap 4, the alignment setting within widgets can change. Currently, this can be found in column widgets and headline widgets. For headline widgets, the default changed from “center” to “left”, so if you changed the settings, you will need to reset them as you intended. Also, the alignment is removed from widgets within the column widgets and will need to be reset.
Additionally, if you added custom styles to your project or created custom widgets or pages, there are changes needed to class names and the CSS. There are quite a few articles out there about these changes already, but you can check out our detailed article as well for some good examples and details as they pertain to the Scrivito ecosystem. If you want to see the code, and since the Scrivito Example App is open source, you can view the Pull Request and inspect all the changes that were required.