Altaro VM Backup Support Centre

Error: "Backup failed due to an error in the Microsoft Shadow Copy component" with Event ID 8193

Last Updated: May 03, 2016 01:54PM CEST


Backup for some VMs failing with Error: "Backup failed due to an error in the Microsoft Shadow Copy component. Retryable Error: The Microsoft recommended way to fix this error is to wait ten minutes and then repeat the operation, up to three times"

 - AND -   

The Application Event log on the target  VM that fails shows the following error:

Log Name:      Application
Source:            VSS
Event ID:          8193
Level:               Error
Volume Shadow Copy Service error: Unexpected error calling routine ConvertStringSidToSid.  hr = 0x80070539. 
   OnIdentify event
   Gathering Writer Data
   Execution Context: Shadow Copy Optimization Writer
   Writer Class Id: {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f}
   Writer Name: Shadow Copy Optimization Writer
   Writer Instance ID: {54d14cb1-7207-4405-9f53-19ed009ee5bd}



The issue may be caused by an invalid entry inside the following registry sub tree:
HKLM\Software\Microsoft\Windows NT\CurrentVersion\ProfileList
Beginning with Windows Vista and Windows Server 2008, the Shadow Copy Optimization Writer 
deletes certain files from volume shadow copies. This is done to minimize the impact of Copy-on-Write I/O during regular I/O on these files on the shadow-copied volume. The files that are deleted are typically temporary files or files that do not contain user or system state.
The SID being referenced in the event can not be resolved. This is due to a “.bak” entry inside the following registry sub tree:
HKey_Local_Machine\Software\Microsoft\Windows NT\CurrentVersion\ProfileList 
Removing the invalid entry from the registry will solve the problem.


  1. On the problematic machine, open the Registry Editor
  2. Browse to HKLM\Software\Microsoft\Windows NT\CurrentVersion\ProfileList
  3. Check for any entries that have a ".bak" value appended. If so, this may be cause the failure when trying to resolve the SID of the writer.
  4. Please backup the registry key first, and then delete the entry with the extra ".bak"
  5. Reboot the problematic machine
  6. Re-try the backup
  7. If the above does not work, then please try to assign a drive letter to the boot partition and then remove it, and again re-try the backup.


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