You see something like the following error message in the Message Logs of the backup:
"FileIO JobId 1435: ESEBackup: BackupSetup failed error c80001f9: Backup is already active."


This error message typically indicates NTBackup or another backup system is already running on the server. Please make sure all other backup processes have been disabled before running a backup with the CFA.
It is not recommended to back up the same servers with multiple systems/software.