A new version of Lucy may involve changes in the Lucy configuration files for add-ons. When you upgrade your Lucy-based project to a new version of Lucy, you need to consider those file changes.
It is recommended to review the changes in the configuration files, and revert them if you do not want them in your project. You revert the changes by using a custom configuration file for that add-on. See How to customize the configuration file of a standard Lucy add-on for more information.
To find the differences between the configuration files of the old Lucy version and the new one, and assess the impact of those differences on your application, use file comparison tools, such as UltraCompare and WinMerge for Windows, or Meld and KDiff3 for Linux, or FileMerge for Mac.