The problem affects domain-joined systems, where authentication failures occur despite credentials being correct. Microsoft's guidance offers a temporary mitigation while a permanent fix is developed, and the company has acknowledged the issue as known.

Affected users should note:

• The issue appears after applying the September 2026 security updates on Windows 11.
• Login attempts with valid domain credentials can fail.
• Microsoft has provided a temporary workaround rather than a full patch at this time.

Administrators managing domain-joined Windows 11 fleets are advised to review Microsoft's workaround and apply it where appropriate until a permanent resolution is released.

Source: Unknown

Has your organization encountered domain login failures since deploying the September 2026 updates, and are you applying Microsoft's workaround?