The error indicates AOFO could not be used for the Shadow Copy operation:

Figure 1
 

Figure 2
 

The following errors may also appear:

Initialization failure on: "\\SERVER\C:". Advanced Open File Option used: Microsoft Volume Shadow Copy Service (VSS).
OFO: Snapshot error (0xfffffed1): A failure occurred querying the Writer status.

Unable to open the item C:\WINNT\system32\dhcp\dhcp.mdb - skipped.

Unable to open the item C:\WINNT\system32\dhcp\j50.log - skipped.

Unable to open the item C:\WINNT\system32\dhcp\tmp.edb - skipped.

As you can see in the Job log shown in Figure 3, the Shadow Copy components have backed up successfully.  Exceptions have  occurred only while backing non-Shadow Copy components, which is not supported by the Microsoft Volume Shadow Copy Service.

Figure 3
 

Cause: These exceptions are generated because "Microsoft Volume Shadow Copy Service" technology is only applicable for backing up Shadow copy components. It can not be used to back up any open or in use files on other resources.

Resolution: In order to protect other in use or open files, the license for the Advanced Open File Option (AOFO) must be registered on the media server. Otherwise only Shadow Copy Components will continue to be protected.

Backup Exec provides different options for AOFO technology that will become available only after entering the valid AOFO license on the media server. (Figure 4)

Figure 4