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Known update issues

KB5121003 – known issues and fixes

KB5121003 is a Microsoft update from Patch Tuesday August 2026, released on 11 Aug 2026. According to the Security Update Guide it fixes 40 vulnerabilities (Windows). Affected according to our entries: Microsoft Windows 11, Microsoft Windows 11 (KB5121003) on HP and Lenovo laptops. Known issues with this update: 2 open.

2Open
0Workaround
0Fixed
40Vulnerabilities fixed

← All known issues

Known issues with KB5121003

OpenKnown issueCommunity reportCheck script

Windows 11 KB5121003: HP laptops report BIOS corruption, Lenovo laptops lose AC power

Reported by users and trade media, not yet confirmed by the vendor: some HP and Lenovo laptops show problems after Windows 11 KB5121003 and the September update. HP laptops reportedly suffer BIOS corruption, failed installation and possibly no OS recovery; Lenovo laptops randomly lose AC power. Neither Microsoft nor Lenovo had commented at the time of the report.

Microsoft · Windows 11 (KB5121003) on HP and Lenovo laptops

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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