NTLMv1 Credentials Are Blocked by Default Since the October 2026 Update: Audit First, Then Fix the Cause Since the October 13, 2026 update, Windows Server 2025 and Windows 11 24H2 or newer block NTLMv1-derived credentials by default. A read-only check script, events 4024 and 4025, real lab output and a safe rollout order. Oct 21, 2026 7 min read Active Directory
