Microsoft has been warning since October 13, 2026 that Windows will no longer recognize ReFS storage devices in the future. The restriction will go into effect with the January 2027 security update. This update is expected to be released on January 12, the second Tuesday of the month. An affected USB stick or SD card will no longer open as usual on a Windows 11 PC. Files stored on it will not be automatically deleted, but Windows will initially be unable to access them.
What are the consequences?
Microsoft developed the ReFS file system as a more modern alternative to NTFS, which Windows has used for many years. Among other things, ReFS is designed to manage large amounts of data more reliably. However, it is not a common option for typical USB sticks and Windows 11 does not support it in all scenarios.
Unfortunately, Microsoft has not given a specific reason for the planned restriction. One possible explanation is compatibility issues: ReFS volumes can cause problems with Windows and other devices or operating systems. However, this is simply a guess.
Administrators can bypass the restriction using a group policy named ‘RefsRemovableDeviceMountPolicy’ or via an entry in the Windows Registry. These configurations are primarily intended for managed computers. Therefore, anyone who is not familiar with them should avoid changing them.
Microsoft classifies the use of ReFS on removable media as unsupported. Although the file system can handle partitions up to 35 petabytes in size (equivalent to 35 million terabytes), this advantage has little practical relevance for everyday use with USB sticks. Windows 11 can now use ReFS for certain data partitions; however, it is not yet designed to be used as a standard system partition.
More information about the intended end of support for ReFS can be found in this blog post.
