their OneDrive account. OneDrive in Windows 8.1 can sync user settings and files, through either the included OneDrive app (originally called SkyDrive, until the name was changed with a Windows update) or File Explorer, deprecating the previous Windows client. Along with the use of reparse points, these changes allow files to be accessed directly from OneDrive as if they are stored locally. The OneDrive app was also updated to include a local file manager. Unlike on Windows 8, use of OneDrive on Windows 8.1 requires the user's Windows account be linked to a Microsoft account; the previous OneDrive desktop client (which did not have this requirement) no longer works on Windows 8.1. Additionally, the Fetch feature does not work on Windows 8.1. In an update on July 4, 2017, OneDrive desktop client started showing an error message to the effect that the local OneDrive folder must be located on an NTFS volume only. Other file systems, including the older FAT32 and exFAT, as well as the newer ReFS were not supported. Microsoft further commented that this was always the requirement; it had merely fixed a bug in which the warning was not displayed. Microsoft also denied this feature having anything to do with the forthcoming OneDrive Files On-Demand. Integration with Microsoft Office Microsoft Office, starting with Microsoft Office 2010 and Microsoft Office for Mac 2011, allows users to directly open or save documents to OneDrive, or simultaneously edit shared documents with other users. Changes are synchronized when a document is saved and, where conflicts occur, the saving user can choose which version to keep; users can also use several different desktop and web programs to edit the same shared document. Microsoft OneNote users can sync one or more of their notebooks using OneDrive. Once a notebook is selected for sharing, OneDrive copies the notebook from the user's computer to OneDrive, and that online copy then becomes the original for all future changes. The originating copy remains on the user's hard drive but is no longer updated by OneNote. Users can switch back to an offline-only version of the notebook by manually changing its location in OneNote, but unpredictable results may occur, including the OneNote application crashing and loss of notebook data under certain conditions. Under such circumstances, re-sharing the Notebook to OneDrive may result in recovery of the lost data. Personal Vault In September 2019 Microsoft announced Personal Vault. It