Windows 11 will stop opening ReFS USB sticks and SD cards in January 2027

Starting with the January 2027 security update, Windows 11 will no longer open removable drives formatted with ReFS. FAT32, exFAT and NTFS media are unaffected, and files on the drives are not deleted. Administrators can bypass the block via the RefsRemovableDeviceMountPolicy Group Policy or the registry.

• The restriction takes effect with the January 12, 2027 patch
• Only USB sticks and SD cards formatted with ReFS are affected
• FAT32, exFAT and NTFS media keep working as before
• A bypass exists via RefsRemovableDeviceMountPolicy or the registry