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SmallPete1's avatar
SmallPete1
Occasional Reader
Jan 05, 2026

Windows 11 S mode AV updates

Father has Windows 11 in S mode. When installing the last couple of Security Intelligence updates for Microsoft Defender hes got "error encountered", which then changed to "completed". Update history states "successfully installed" on related entries. Does not make sense that something can be successfully installed if an error occurred during the install. A little nervous now that the only av available for S Mode is not seemingly being updated properly.  Any suggestions?

Update management

1 Reply

  • AladinH's avatar
    AladinH
    Iron Contributor
    Jan 06, 2026

    Hi SmallPete1​,

    This behavior is normal in Windows 11 S Mode. Microsoft Defender Antivirus is the only AV allowed, and sometimes Security Intelligence updates may briefly show an error before automatically retrying and completing. Even if an error appears at first, the update is usually applied successfully, which is why the history may show “successfully installed”. Your protection remains fully active.

    To double-check, you can open Windows Security > Virus & threat protection > Check for updates and confirm the Security Intelligence version matches the latest on Microsoft’s official definitions page. Running a quick or full scan after updating can also confirm everything is working correctly. This is fully supported by Microsoft and is the recommended way to ensure Defender stays up to date in S Mode.

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