Windows September updates break SMBv1 shares: Workarounds and user feedback
Microsoft’s September 2025 security updates have broken connectivity to SMBv1 shares over NetBIOS over TCP/IP (NetBT), disrupting Windows client and server systems that still rely on this legacy protocol. This article explains what SMBv1 is, why it remains in use despite being deprecated, and the serious security risks that come with it. We’ll cover the details of the September updates, their impact on affected systems, and the available workarounds for organizations struggling to restore functionality. Finally, we’ll look at user feedback and long-term recommendations for migrating away from SMBv1 to more secure and modern protocols.