Windows Server · 2025 · Release · Security update (Patch Tuesday)
October 14, 2025—KB5066835 (OS Build 26100.6899)
- Release
- Cumulative update
- KB5066835 — Microsoft's article, opens in a new tab
Windows Server 2025: Current LTSC release
Microsoft's known issues — KB5066835
- Issue Known issue Active Directory domain controllers (DC) running on Windows Server 2025 and also running the schema master Flexible Single Master Operation (FSMO) role , will allow duplicate entries in attributes of schema objects. Commonly affected attributes include auxiliaryClass , possSuperiors , mayContain with values such as msExchBaseClass , msExchContainer , and msExchVirtualDirectoryFlags . When this occurs, Active Directory replication fails with a schema mismatch error, such as error 8418: The replication operation failed because of a schema mismatch between the servers involved." This issue can be observed when running Exchange Server setup forestprep and the schema master role for Active Direct Workaround: This issue is addressed KB5068861 . This issue is addressed in KB5068861 . This issue is addressed in KB5070773 . Windows Server 2025 users aren’t affected, and no action is required. To learn how this issue affects Windows 11, see the following: Windows 11, version 25H2 Windows 11, version 24H2
Known issues — reported on the forum
- Issue Fix Windows Server 2025 WinRE USB Input Bug After KB5066835—Patch to KB5070773
- Issue WinRE Startup Fix: March 2026 KB5075039 Resolves October 2025 Regression
- Issue Windows October 2025 Update Regression Breaks WinRE and Localhost
- Issue Windows 11 Update Chaos: Swarm Teams Fix XAML Regressions and Boot Issues
In the news
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