Microsoft plans to block some USB drives in Windows 11 in January 2027

Microsoft plans to stop Windows 11 from opening USB sticks, SD cards and other removable drives formatted with ReFS through its January 2027 security update, PCWorld said in its October 22 report. The change would prevent normal access to files on affected drives, not automatically delete those files.

Microsoft already classifies ReFS use on removable media as unsupported and has warned about the coming restriction since October 13, 2026.

Which drives are affected?

ReFS stands for Resilient File System. A file system determines how a drive organises stored files. Microsoft developed ReFS as a newer alternative to NTFS, designed to manage large amounts of data more reliably. It is used on backup servers but is not a common format for typical USB sticks.

The planned restriction does not affect drives formatted with FAT32, exFAT or NTFS. Many USB sticks and SD cards use FAT32 or exFAT, so most users are unlikely to notice a change. The restriction matters to people who have formatted a removable drive with ReFS themselves or use a drive already set up that way.

Administrative exceptions and timing

Administrators can bypass the restriction through Group Policy, a tool for managing computer settings, or the Windows Registry, which stores system settings. These exceptions are primarily intended for managed computers rather than ordinary access. People unfamiliar with those settings should avoid changing them.

Microsoft has not given a specific reason for the restriction. The planned next step is the January 2027 security update, expected on January 12; that is an expected release date, not a confirmed rollout date.