Dropbox recently announced the end of life for the API used by many products to integrate with them including all old versions of Simple Control and Roomie Remote.
In V5, we no longer use Dropbox, so we have already migrated away and therefore this is not a concern for current users. For those users still on any older release, the Simple Service Backup option is one alternative already part of the older releases.
Please plan to migrate away from Dropbox as your backup solution before the end of the year. You can simply copy a Dropbox Backup (the set of files plus images folder if applicable) to your iCloud Simple Control folder, and Restore from iCloud using V5 as one good solution if you need to restore. Also remember that installing V5 alongside V4 does not require any backup/restore. The V4 configuration is automatically adopted and upgraded by V5.