Why did my parameters disappear after upgrade?
If the structure of parameter changes (parameter added, modified, or removed) in the release you are upgrading to - then the default values are restored, and you may lose the configuration. We are striving to notify users with major changes, usually in the major application version. Nevertheless, it is recommended to back up the configuration always before upgrading.
More about this topic can be found here.
If you forgot to save the configuration before the upgrade, you can upload the old firmware back and the configuration will be restored (unless you executed "save" command in the new firmware).
The same principle works with permanents. If the structure of permanents changes, the old permanents are lost. This is problematic, especially for the ODO meter. If this happens, it is noted in the changelog and the major version is changed.