RHDS backup fails "ERROR: Error: The backup create task has failed with the error code: (None)"

Issue

• RHDS backup fails "ERROR: Error: The backup create task has failed with the error code: (None)"

$ dsconf -v -D "cn=Directory Manager" ldap://localhost:5389 backup create
...
DEBUG: cn=backup_2021-08-11T17:49:34.483894,cn=backup,cn=tasks,cn=config getVal('nsTaskExitCode')
DEBUG: cn=backup_2021-08-11T17:49:34.483894,cn=backup,cn=tasks,cn=config getVal('nsTaskLog')
DEBUG: cn=backup_2021-08-11T17:49:34.483894,cn=backup,cn=tasks,cn=config getVal('nsTaskWarning')
DEBUG: cn=backup_2021-08-11T17:49:34.483894,cn=backup,cn=tasks,cn=config getVal('nsTaskExitCode')
DEBUG: cn=backup_2021-08-11T17:49:34.483894,cn=backup,cn=tasks,cn=config getVal('nsTaskLog')
DEBUG: cn=backup_2021-08-11T17:49:34.483894,cn=backup,cn=tasks,cn=config getVal('nsTaskWarning')
DEBUG: The backup create task has failed with the error code: (None)
Traceback (most recent call last):
  File "/usr/sbin/dsconf", line 134, in <module>
    result = args.func(inst, None, log, args)
  File "/usr/lib/python3.6/site-packages/lib389/cli_conf/backup.py", line 20, in backup_create
    raise ValueError("The backup create task has failed with the error code: ({})".format(result))
ValueError: The backup create task has failed with the error code: (None)
ERROR: Error: The backup create task has failed with the error code: (None)
$