Event log automatic backup completed
The security event log was automatically archived and cleared based on retention policy.
Event ID 1105 occurs when Windows automatically backs up the event log to an archive file (`Archive-Security-*.evtx`) upon reaching capacity when configured to 'Archive the log when full, do not overwrite events'.
Failure Reason / Root Cause:
Standard automated log rotation and archiving behavior configured via Group Policy.
Raw Event XML snippet
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Microsoft-Windows-Security-Auditing" Guid="{54849625-5478-4994-A5BA-3E3B0328C30D}" />
<EventID>1105</EventID>
<Version>0</Version>
<Level>0</Level>
<Task>12544</Task>
<Opcode>0</Opcode>
<Keywords>0x8020000000000000</Keywords>
<TimeCreated SystemTime="2026-07-17T09:54:44.851Z" />
<EventRecordID>1048576</EventRecordID>
<Correlation />
<Execution ProcessID="612" ThreadID="1024" />
<Channel>Security</Channel>
<Computer>DC01.enterprise.internal</Computer>
<Security />
</System>
<EventData>
<Data Name="SubjectUserSid">S-1-5-18</Data>
<Data Name="SubjectUserName">SYSTEM</Data>
<Data Name="SubjectDomainName">NT AUTHORITY</Data>
<Data Name="SubjectLogonId">0x3e7</Data>
<!-- Event telemetry fields specific to Event log automatic backup completed -->
</EventData>
</Event>Recommended actions
- Ensure automated log collection agents immediately collect and ingest newly generated archive files.