Characters you can’t use in OneDrive and SharePoint file names

The problem

Nine characters are not allowed anywhere in a OneDrive or SharePoint file or folder name. A single one of them is enough to stop an item from syncing.

This guide is a character reference. For reserved names, lock files and spaces, see the guide on invalid file names.

Characters OneDrive and SharePoint reject

Leading and trailing spaces are also not allowed. # and % are supported, but some organizations have not enabled them yet. & is not supported by Office 2010, and Office desktop apps cannot save into a folder whose name contains a semicolon (;).

Symptoms

• The item shows a sync error in File Explorer and is listed in the OneDrive activity center.
• Uploading the file in a browser is refused because of its name.
• Files copied from a Mac, a NAS or an archive sync partially, with some items missing online.

Causes

• Names created outside Windows

  Windows File Explorer does not let you type these characters, so on a Windows PC they nearly always come from macOS, Linux, Android, network storage or extracted archives.

• Dates and versions in names

  Names such as "Report 11/07" or "Final: v2" are natural to type on systems that allow them, and they are the most common source of slashes and colons.

• Substituted characters

  Some tools replace forbidden characters with look-alike Unicode characters when copying files to Windows. These names may sync, but they look odd and are hard to search for.

How to fix it

1. List names that contain unsupported characters

   This read-only PowerShell command lists every file and folder below your OneDrive folder whose name contains one of the nine characters. Use $env:OneDriveCommercial for a work or school account.

   Get-ChildItem -LiteralPath $env:OneDrive -Recurse -Force -ErrorAction SilentlyContinue |
     Where-Object { $_.Name -match '[\\/:*?"<>|]' } |
     Select-Object FullName

2. Choose one replacement rule

   Decide on a single rule, for example replacing every unsupported character with a hyphen. Consistent names are easier to search for and less likely to collide.

3. Check for collisions before renaming

   After replacement, "Plan: A.docx" and "Plan- A.docx" become the same name. Rename one of them deliberately so OneDrive does not create a conflict copy.

4. Rename and let OneDrive sync

   Rename items in File Explorer (F2) or in OneDrive in your browser. Pause syncing first if you are renaming many items, then resume.

When OneDriveSyncFixer helps

Microsoft documentation

• Restrictions and limitations in OneDrive and SharePoint (opens in a new tab)support.microsoft.com

This guide summarizes Microsoft’s published guidance in our own words. Microsoft documentation remains the authoritative source.