A netbackup upgrade won't help you with status code 84. There are 4 type of reason for status code 84

• Bad media  or bad tape drives -  Check for SCSI sense keys, they can assist you in locating the problem.
• Tape drive firmware problem  - Is the  tape drive firmware up to date ?
• Connection related issue (SCSi or SAN related)
• Dust

Long time ago I used  a tool called "scsitool box ".  With that tool you can run a series of test to establish the quality of drive/media. HP also provide a tool called "HP StorageWorks Library and Tape Tools" it may do the same job.

If you are on Linux, sg_logs can do the job:

sg_logs -p=2  /dev/nst0
    HP        Ultrium 3-SCSI    L29S
Write error counter page
  Errors corrected without substantial delay = 52
  Errors corrected with possible delays = 0
  Total operations = 0
  Total errors corrected = 0
  Total times correction algorithm processed = 58
  Total bytes processed = 723
  Total uncorrected errors = 0
congo:/usr/bin # sg_logs -p=3  /dev/nst0
    HP        Ultrium 3-SCSI    L29S
Read error counter pageg
  Errors corrected without substantial delay = 5
  Errors corrected with possible delays = 0
  Total operations = 0
  Total errors corrected = 0
  Total times correction algorithm processed = 5
  Total bytes processed = 61
  Total uncorrected errors = 0