Machine Identity Isolation policies can reject valid credentials unless controllers meet the Server 2025 functional level Microsoft September cavalcade of cockups continued with confirmation that something is amiss with Active Directory domain logins. The issue , which affects Windows 11 versions 24H2, 25H2, and 26H1, was added to Microsoft ever lengthening list of known problems on September 16. It stems from changes to Machine Identity Isolation in the September 2026 security update...
