Microsoft: Recent Windows updates cause login issues on some PCs

Microsoft confirmed that Windows updates released on or after August 29, 2025 add SID‑uniqueness checks that can break Kerberos and NTLM authentication on systems with duplicate Security Identifiers (SIDs) — typically produced by cloning/imaging without Sysprep — affecting Windows 11 (24H2, 25H2) and Windows Server 2025, causing RDP failures, access denied errors and SEC_E_NO_CREDENTIALS events; Microsoft recommends rebuilding affected systems with supported imaging procedures or obtaining a temporary Group Policy from Support.