Always save out actions and brushes to .atn and .abr files, and keep them in a safe place so they can be easily reloaded.
Actions, brushes and other preferences do not automatically carry over in a major version update.
This stuff is all stored in the “Adobe Photoshop <version> Settings” folder in your user account, which is version specific. Each version has its own settings folder.
Migrating preferences is an option in the installer, but there’s a good chance migrating preferences might introduce new problems, so I don’t generally recommend it.
That is why