You get this message when backing up “C:\xxx\yyy\zzz.txt” because another application has held a read-exclusive lock on “C:\xxx\yyy\zzz.txt”. The backup agent, therefore, is unable to open the file to read its content. Please try the followings to resolve this problem:

Enable the Volume Shadow Copy option for the corresponding backup set if you are on Windows 2003 or XP.
If you are on an older version for Windows, you may need to obtain a generic “Open File Manager” in order to backup the locked files.

If the locked file is not important (e.g. C:\pagefile.sys), simply exclude the locked file from your backup source. By doing so, this message will not appear again.

If the locked file is a database file held open by one of our supported applications (e.g. Microsoft SQL Server, Microsoft Exchange Server, Oracle, Lotus Domino/Notes, MySQL), simply use the corresponding add-on module provided to backup the database. This way, you can backup the database you want (using the application specific APIs) without accessing the database file directly.

If the locked file is a file held open by some other third party applications, you can use the [Pre/Post Command Line Tool] to shutdown/restart the application that is locking the file before/after a backup job to make sure that no locks will be placed on files that you need to backup.