Specifically, I have the following (overlapping) questions:
1.) is the upgrade purely a matter of selecting a new 2.0 compatible theme? Or must one do some change on the backend/admin?
2.) can one rollback to 1.0? For instance if the answer to 1.) is “yes”, upgrading is just a matter of publishing a 2.0 theme, can one rollback to 1.0 by simply publishing a vintage theme?
Upgrading a Shopify theme from version 1.0 to 2.0 is not just a matter of selecting a new 2.0 compatible theme. The update involves significant changes to the theme’s code, structure, and functionality. This means that updating an existing theme to 2.0 requires making changes to the theme’s code, including HTML, CSS, and JavaScript files.
It is not possible to rollback a theme from 2.0 to 1.0 once it has been updated. Once a theme has been upgraded to 2.0, the changes made to the theme’s code are irreversible. Therefore, it is recommended to make a backup of your theme before upgrading to ensure that you have a copy of the previous version of the theme in case you need to rollback.