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KB Details - KB5124008

KB5124008

Important ⚠️ Yes
Title
September 8, 2026—KB5124008 (OS Builds 26200.9445 and 26100.9445) | Microsoft Support
Severity
Important
Known Issues
⚠️ Yes
Known Issues Count
1
Release Date
2026-09-08
OS Builds
26200.9445, 26100.9445
Actions Recommended
Ensure the boot.stl file is included as part of the installation media.
Known Issues Details
#1 - Potential issue (from database)
Status: Unknown
Symptoms: Microsoft combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). For general information about SSUs, see Servicing stack updates.
Deployment
If you deploy dynamic updates such as this update to an existing Windows image, ensure the boot.stl file is included as part of the installation media. Failure to include the file might prevent devices from successfully starting from the installation media and can result in error code 0xc0430001.
To ensure the boot.stl file is included as part of the installation media, do one of the following:
For information about how to apply Dynamic Update packages to existing Windows images, see Update Windows installation media with Dynamic Update.
To install this update, use one of the following Windows and Microsoft release channels.
For a list of the files provided in this update, download the file information for cumulative update KB5124008.
For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5124007) - version 26100.9441.
Windows monthly updates explained
Description of the standard terminology used for Microsoft software updates
Microsoft Store for Business and Education with Configuration Manager
Get updates for apps and games in Microsoft Store

Workaround: N/A
Affected: N/A
Description
Known issue status retained from previous database evidence. Detailed issue extraction was inconclusive in this run.

Evidence snapshot: Microsoft combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). For general information about SSUs, see Servicing stack updates.
Deployment
If you deploy dynamic updates such as this update to an existing Windows image, ensure the boot.stl file is included as part of the installation media. Failure to include the file might prevent devices from successfully starting from the installation media and can result in error code 0xc0430001.
To ensure the boot.stl file is included as part of the installation media, do one of the following:
For information about how to apply Dynamic Update packages to existing Windows images, see Update Windows installation media with Dynamic Update.
To install this update, use one of the following Windows and Microsoft release channels.
For a list of the files provided in this update, download the file information for cumulative update KB5124008.
For a list of the files provided in the servicing stack update, download the file information for the SSU (KB5124007) - version 26100.9441.
Windows monthly updates explained
Description of the standard terminology used for Microsoft software updates
Microsoft Store for Business and Education with Configuration Manager
Get updates for apps and games in Microsoft Store
Microsoft Article
AI Enriched At
September 12, 2026 at 1:40 AM
Date Added
September 11, 2026 at 5:36 PM

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