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Known update issues

KB5124012 – known issues and fixes

KB5124012 is a Microsoft update from Patch Tuesday September 2026, released on 8 Sep 2026. According to the Security Update Guide it fixes 103 vulnerabilities (Windows). Affected according to our entries: Microsoft Windows 11, Version 26H2. Known issues with this update: 1 with workaround, 1 fixed.

0Open
1Workaround
1Fixed
103Vulnerabilities fixed

← All known issues

Known issues with KB5124012

WorkaroundKnown issue

Windows 11 26H2: USB audio devices might fail to start or produce no sound

Some USB Audio Class 1.0 devices might fail to start or produce no audio after installing Windows 11, version 26H2. Microsoft lists the same issue for other Windows client and server versions, where it originates from the September 8, 2026 security updates. For 26H2 the vendor status is Mitigated and a fix in a future Windows update is still being worked on.

Microsoft · Windows 11, Version 26H2

FixedKnown issueFix scriptCheck script

Windows 11 26H2: Domain-joined devices may lose their trust relationship with the domain

After installing Windows 11 version 26H2, Credential Guard protected machine accounts may lose their secure channel to an on-premises Active Directory domain. The cause is Machine Identity Isolation (MII), which Windows now honours; it is only supported with Windows Server 2025 domain controllers at Domain Functional Level 2025 or above. Microsoft has resolved the issue with updates released on 2026-09-22 and later.

Microsoft · Windows 11, Version 26H2

Where the information comes from

We continuously read the vendors’ official sources, community reports and trade media and summarise them in our own words, with a link to the source:

  • Microsoft: Windows release health (Windows 10/11, Server 2016 to 2025), Windows message center, known issues of Microsoft 365 Apps (Outlook, Excel, Word, PowerPoint), Edge, Intune, Autopilot, Windows 365 and Entra Connect, Microsoft KB articles with timelines, Exchange and Windows IT Pro blogs, optionally Microsoft 365 service health and message center
  • other vendors: Veeam KB, Citrix (known issues), Ubuntu and Debian (regressions), Broadcom (VMware), Fortinet, Cisco, Mozilla, Let’s Encrypt
  • community (title, short excerpt and link only, without the names of the authors): Microsoft Q&A, Microsoft Tech Community (discussions), Veeam R&D Forums, Eleven Forum
  • targeted web research with AI (Claude), e.g. on the updates of the month – this also finds discussions on Reddit and in forums; such entries are labelled as community reports until the vendor confirms them
  • early warning from trade media (title and link only): Born’s Tech and Windows World, BleepingComputer, AskWoody, Windows Latest, Windows Central, gHacks, The Windows Club, Deskmodder, Dr. Windows, WindowsArea, Frankys Web, heise online

Summary and translation with AI (Claude by Anthropic) – without any data of visitors.

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