Windows 11 Login Issues Linked to Security Protections

Microsoft has acknowledged login issues affecting Windows 11 and Windows Server 2025, which have arisen due to new security measures. These issues impact Windows 11 versions 24H2 and 25H2, and are linked to the August 29 release of update KB5064081 and the September 9 release of KB5065426. The new security protections have disrupted Kerberos and NTLM authentication in systems with duplicate Security IDs (SIDs).

Impact and Symptoms

The primary symptoms include repeated credential prompts, failure to access resources despite valid credentials, and remote desktop connection issues. Shared network folders may become inaccessible via IP address or hostname. Additionally, errors appear in the Event Viewer, indicating authentication failures.

Recommended Solution

To address this problem, Microsoft advises that devices with duplicate SIDs be rebuilt to ensure each has a unique SID. This is seen as the only permanent solution to the issue. Microsoft has made detailed guidance available to assist in this process.

Technical Context

• Issue confirmed on Windows 11 24H2 and 25H2 after KB5064081 (2023-08-29).
• The challenge extends to Windows Server 2025 following KB5065426 (2023-09-09).
• Security enhancements interfering with Kerberos and NTLM protocols.
• Systems afflicted require SID rectification to restore functionality.

Update: 23 Jun 2026