A VSS error in this backup job has resulted in the loss of most of your backup history

Error code


Applies to



BackupAssist v8.4 and later


In rare instances, VSS can delete backup history to free up shadow copy space, when the backup destination is unable to maintain the minimum write speed access required during a System Protection backup.

The slow write access is usually due to:

  • Underperforming hardware
  • Periods of abnormally high disk activity within the backup destination.
  • High network congestion during the backup window


Below is a series of steps that you should follow to find a resolution to this error.

Troubleshooting step 1 - Check the Event Viewer for warnings or errors

If there is a hardware issue with a device, Windows will usually provide entries about this issue in the Event Viewer. This additional information can be used to help resolve the error.

Open Event Viewer by clicking on Start > Run > Eventvwr to see if there are any specific warnings or errors (specifically from sources volsnap, disk or NTFS) being generated from the system during the backup process. You will specifically want to look at the Application and System logs in this instance.

Below is a screen shot of an example of what a log may look like when history has been lost.

If you find such events being logged, these will need to be addressed so that history loss does not occur in future.

SPM event

If this is the case, you need to review the hardware being used as the backup destination.

Troubleshooting step 2 - Update any drivers or firmware for the backup destination

If you are using a Network Device

Windows can sometimes state that hardware is working when you check it in Device Manager. However, due to outdated firmware and drivers, issues such as underperformance and failing functionality can occur.

Try upgrading the firmware and drivers for the backup destination (in particular if it is a NAS device). You may need to do this by visiting the manufacture's website as they provide firmware and hardware updates as downloadable files.

It is also recommended that you download and run any hardware diagnostic tools, which help perform consistency checks on the destination and attempt to find any errors.

If you are using a Local Device

When backing up to a local device (and getting this warning in the backup report) it is recommended that you run a consistency check (chkdsk scan) on the drive and also a defragmentation process.

Please review the following document from Microsoft on the use of chkdsk: https://technet.microsoft.com/en-us/magazine/ee872425.aspx

If any of the problems described in the article are occurring, reschedule one of the processes to a later time to avoid the conflict.

More information on defragmentation is located at http://windows.microsoft.com/en-au/windows/improve-performance-defragmenting-hard-disk#1TC=windows-7.

Troubleshooting step 3 - For Network destinations: run a secondary backup

If you are backing up to a network based destination, it is recommended that you run a second backup to a locally connected device (internal drive or external USB drive) in conjunction with your current backup. By running a second backup, your original backup will eventually generate this warning again - however the second job to the local destination should not. This will prove that the original destination is the cause of the issue and will require further investigation or possibly replacing.

Troubleshooting step 4 - Enable Shadow Protect Mode within your backup job

It is not a good thing to have Shadow Protect Mode turned on permanently. It is just a temporary measure to avoid further history loss while a permanent solution is implemented.

Shadow Protect Mode is designed to prevent history loss. However with this enabled, it can actually hide the real cause of the history loss. It is recommended that you perform the investigation steps above before enabling this option.

To enable Shadow Protect Mode, follow the steps outlined below:

  1. Open BackupAssist.
  2. Select Manage Backup Jobs.
  3. Select the backup job.
  4. Select Edit from the top menu.
  5. Select Imaging Options from the options on the left.
  6. Under VSS Backup Mode, tick Shadow Copy Protection Mode.

Manage : Imaging options

Note: Shadow Protect Mode will only help protect the destination from history loss. It will not provide a permanent solution to the reason why the history loss occurred in the first place.

Last updated


Further assistance

8th June 2017

10th Mar 2015

BackupAssist Support page