An anonymous reader quotes a report from Ars Technica: OneDrive users around the world have been upset to discover that with its latest update, Microsoft's cloud file syncing and storage system no longer works with anything other than disks formatted with the NTFS file system. Both older file systems, such as FAT32 and exFAT, and newer ones, such as ReFS, will now provoke an error message when OneDrive starts up. To continue to use the software, files will have to be stored on an NTFS volume. While FAT disks can be converted, ReFS volumes must be reformatted and wiped. This has left various OneDrive users unhappy. While NTFS is the default file system in Windows, people using SD cards to extend the storage on small laptops and tablets will typically use exFAT. Similarly, people using Storage Spaces to manage large, redundant storage volumes will often use ReFS. The new policy doesn't change anything for most Windows users, but those at the margins will feel hard done by. Microsoft said in a statement that it "discovered a warning message that should have existed was missing when a user attempted to store their OneDrive folder on a non-NTFS filesystem -- which was immediately remedied." According to Ars, Microsoft's position, apparently, is that OneDrive should always have warned about these usage scenarios and that it's only a bug or an oversight that allowed non-NTFS volumes to work.