Symptoms

Volume Shadow Copy Service (VSS) backups are failing with the VSS Event ID 8193 generated on the client. VSS backups fail with the errors: avvss Error <8327>: Unable to successfully process [Wo], targets System State/BootableSystemState/ASR (C:) System State/BootableSystemState/System System State/BootableSystemState/Registry The VSS error Event ID 8193 was found on the server with the statement: Volume Shadow Copy Service error: Unexpected error calling routine ConvertStringSidToSid([S-x].bak). hr = 0x80070539, The security ID structure is invalid 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: {8db89871-83d2-4e39-b4fd-34b73f889c10} Examining the registry (with the Registry Editor tool regedit) found the following entry located at HKLM\Software\Microsoft\Windows NT\CurrentVersion\ProfileList:

Cause

The error is due to invalid entries in the registry, where .bak entries are located at HKLM\Software\Microsoft\Windows NT\CurrentVersion\ProfileList.

Resolution

Consult to the System administrator or Microsoft support to apply the following recommended solution: Open the Registry Editor with regedit.Go to HKLM\Software\Microsoft\Windows NT\CurrentVersion\ProfileList.Find the entry that ends with the ".bak"Backup the registryDelete that entry with the ".bak" extension.Reboot the server 

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