If you get this error while you are doing MS SQL or MS Exchange backup, please try to use an UNC path (e.g. //server/share) in "Temporary directory for storing backup files" under [Backup Source Settings]. Please make sure that your backup software client is on the same machine as your MS SQL or MS Exchange. Please also ensure that you have included the appropriate “Network Resources Authentication for Windows” information in the "General" section of the backup set.
For MS SQL Server, you may want to check whether if it can spool the database file correctly by running the following command:
(Windows Authentication mode)
osql -E -Q "DECLARE @dbname char(64) SET @dbname = 'xxx' BACKUP DATABASE @dbname TO DISK = '//server/share/abc.txt' WITH SKIP"
(SQL Server Authentication mode)
osql -U USERNAME -P PASSWORD -Q "DECLARE @dbname char(64) SET @dbname = 'xxx' BACKUP DATABASE @dbname TO DISK = '//server/share/abc.txt' WITH SKIP"
USERNAME/PASSWORD = the database username/password
xxx = the database that you would like to backup
//server/share/abc.txt = the location for the database spooling file