Volume Shadow Copy Service error: Unexpected error calling routine ConvertStringSidToSid, The security ID structure is invalid.

Error on Exchange 2007 application log

Can anyone tell me what this means?

There is no VSS running except for the backup which is reported as working fine and all of the log files etc. appear to be correct:::

Log Name:      Application
Source:        VSS
Date:          02/09/2019 23:30:07
Event ID:      8193
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      %computername%.domain.local
Description:
Volume Shadow Copy Service error: Unexpected error calling routine ConvertStringSidToSid(S-1-5-21-643322192-3791837119-3815354684-1162.bak).  hr = 0x80070539, The security ID structure is invalid.
.

Operation:
   OnIdentify event
   Gathering Writer Data

Context:
   Execution Context: Shadow Copy Optimization Writer
   Writer Class Id: {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f}
   Writer Name: Shadow Copy Optimization Writer
   Writer Instance ID: {5d879f61-98fa-409b-8b39-6f503c928c01}
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="VSS" />
    <EventID Qualifiers="0">8193</EventID>
    <Level>2</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2019-09-02T22:30:07.000000000Z" />
    <EventRecordID>977849</EventRecordID>
    <Channel>Application</Channel>
    <Computer>%computername%.domain.local</Computer>
    <Security />
  </System>
  <EventData>
    <Data>ConvertStringSidToSid(S-1-5-21-643322192-3791837119-3815354684-1162.bak)</Data>
    <Data>0x80070539, The security ID structure is invalid.
</Data>
    <Data>

Operation:
   OnIdentify event
   Gathering Writer Data

Context:
   Execution Context: Shadow Copy Optimization Writer
   Writer Class Id: {4dc3bdd4-ab48-4d07-adb0-3bee2926fd7f}
   Writer Name: Shadow Copy Optimization Writer
   Writer Instance ID: {5d879f61-98fa-409b-8b39-6f503c928c01}</Data>
    <Binary>2D20436F64653A20534543534543524330303030303931302D2043616C6C3A20534543534543524330303030303930332D205049443A202030303030323434302D205449443A202030303030383830302D20434D443A2020433A5C57696E646F77735C73797374656D33325C76737376632E6578652020202D20557365723A204E616D653A204E5420415554484F524954595C53595354454D2C205349443A532D312D352D313820</Binary>
  </EventData>
</Event>

Run regedit.exe and find:

HKey_Local_Machine\Software\Microsoft\Windows NT\CurrentVersion\ProfileList

Backup the ProfilesList key first

See if there is an entry in there for a non-existent user and if so delete the key of that user SID

Reboot.

See if the issue is resolved...