Microsoft is addressing an issue with Active Directory functionalities for certain Windows Server 2025 systems after the installation of the September 2025 security update (KB5065426). The problem affects applications using Active Directory directory synchronization (DirSync), particularly for large security groups exceeding 10,000 members, resulting in incomplete synchronization. To resolve this, IT administrators can implement the Known Issue Rollback (KIR) Group Policy on affected devices. For non-managed devices, a temporary fix involves adding a registry key at the specified path with a specific name, type, and value. Additionally, Microsoft is working on resolving a bug affecting Windows updates on Windows 11 24H2 and Windows Server 2025, as well as addressing smart card authentication issues and HTTP/2 localhost connection disruptions following recent security updates.