Microsoft's monthly Patch Tuesday updates for Windows are generally meant to fix problems, but that isn't how it always goes.

According to Microsoft's documentation and reporting from Bleeping Computer, the VPN connection issues affected "IPSEC connections which contain a Vendor ID," as well as L2TP and IPSEC IKE VPN connections in Windows 10, Windows 11, and Windows Server versions 2022, 20H2, 2019, and 2016.

Windows' built-in VPN client seems to be the most commonly affected, but third-party VPN clients using these kinds of connections could also run into the error.

The latest round of Patch Tuesday updates also caused some problems for Windows Server, including unexpected reboots for domain controllers and failed boots for Hyper-V virtual machines.

The ReFS filesystem was supported in the consumer versions of Windows for a few years, though Microsoft removed the ability to create ReFS drives a few years ago, restricting it to servers and the enterprise editions of Windows.