Severity Level 10
There is no current database backup. This log backup cannot be used to roll forward a preceding database backup.
To restore the database after failure, you must begin either with a full database backup, or with a partial or complete set of file backups. Either this database has never been backed up, or a BACKUP LOG statement was executed after switching from the Simple Recovery model to Full or Bulk-Logged recovery before a database or file backup was performed. Therefore, the log backup just completed is not useful.
Perform a full database backup before backing up the log.