I run LMS 3.0.1 (installed last year). The daily backups were OK until a couple of weeks.
When trying to manually backup, I have the same error :
Reason ERROR(288): no database files available for the installed applications. Nothing to backup.
Any help, please
It looks like you have destroyed the contents of NMSROOT/backup/manifest. If this is the case, you either need to restore this directory from a OS file system backup, or reinstall all of LMS. The NMSROOT/backup directory must NEVER be touched.