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Windows Server 2025 AD DS synchronization disruption after KB5065426

Service Disruption
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Last updated
Happening score
H score 0
1 unique sources, 2 articles

Summary

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A Windows Server 2025 known issue is disrupting Active Directory Domain Services (AD DS) synchronization, causing incomplete sync for large AD security groups and risking directory inconsistency. The bug affects systems that installed the September 2025 Windows security update (KB5065426) or later updates and can break Microsoft Entra Connect Sync workflows. Administrators can mitigate the problem with a Known Issue Rollback Group Policy or a temporary registry change. A full fix is rolling out before next month's Patch Tuesday.

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Timeline

  1. 20.10.2025 18:27 3 articles · 7mo ago

    Microsoft rolls out fix for Windows Server 2025 AD DS sync issue

    Initial Disclosure

    Microsoft is rolling out a fix for a known issue affecting Windows Server 2025 systems that installed the September 2025 Windows security update (KB5065426) or later, where Active Directory Domain Services (AD DS) synchronization and Microsoft Entra Connect Sync can produce incomplete synchronization for large AD security groups exceeding 10,000 members. Administrators can apply a Known Issue Rollback Group Policy on managed devices or use the temporary registry value 2362988687 under Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Policies\Microsoft\FeatureManagement\Overrides until the fix reaches all customers next month.

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