In CFT, this can be manifested by an error code, 115, "Permission Denied".  This can happen because the user launching CFt does not have rights to the NAS device.

1- Open Windows Explorer and ensure that the NAS is accessible with the CFT Windows user.  Ensure that read/write access is granted.  Ensure that the location is mounted and assigned a drive letter.
2 - Ensure that this issue does not OCCUR by starting CFT manually (not as a service), with a user that has rights to the NAS
3- If mapped drive is to be used ensure the UCONF file is set accordingly, collect the result of a listuconf command and check the rootdirs values for the mapped drive.
4- If the Windows Service failed to connect to the the UNC path files, this is a permission issue, as the Windows Service isn''t logged in as a user (even when a specific user has been set for that service).  You must set the logon type to use assigned user credentials. (ServiceProcessInstaller.Account = System.ServiceProcess.ServiceAccount.LocalService).Me.ServiceProcessInstaller1. (Account, Username, Password properties)...
5- Ensure the CFT Service is using the assigned CFT user