Local Preflight / Mac to OneDrive
Moving files from a Mac to OneDrive or SharePoint
macOS accepts almost any file name. OneDrive and SharePoint don't. Folders built up on a Mac over the years almost always contain names that fail in the move. Here is what to look for and how to find it before you start.
Mac names that fail in OneDrive and SharePoint
| What you see in Finder | Why it fails |
|---|---|
Q&A: launch plan, Invoice 12/2024 | A / typed in Finder is stored as : on disk. Both are invalid in OneDrive and SharePoint. |
What's next?.key, Draft*.pages, "Final".pdf, A|B test, <old> | ? * " | < > are allowed on a Mac and blocked by Microsoft. |
| A folder with a custom icon | It contains a hidden file named Icon + carriage return, which can't be stored. |
Photos (trailing space), Notes | Leading and trailing spaces are not allowed and are invisible in Finder. |
Old version. | Windows drops trailing periods, so colleagues on Windows get sync conflicts. |
~$Budget.xlsx | Leftover Office lock file. Not allowed, and safe to delete. |
Report.pdf and report.pdf in one folder | Only possible on case-sensitive Mac volumes. SharePoint treats them as the same name. |
Full list of Microsoft's rules: OneDrive and SharePoint file name rules. Hidden files such as .DS_Store aren't a problem and aren't needed in SharePoint.
Why Microsoft's migration tools don't help on a Mac
The SharePoint Migration Tool, which can scan a folder before migrating, requires Windows 10 or Windows Server. Microsoft's FastTrack preflight script is Windows PowerShell. On a Mac you normally find problems only after the OneDrive app or the browser upload refuses a file, and it reports them one at a time.
Free check in Terminal
If you are comfortable with Terminal, these commands list the most common problems. Run them from inside the folder you plan to move (cd into it first):
Names with invalid characters:
find . -name '*[:*?"<>|\\]*'Names starting or ending with a space:
find . -name ' *' -o -name '* 'These don't cover reserved names, ~$ and _vti_, hidden control characters, case-only duplicates or path length. They also give no suggested fix, but they cost nothing and are a good first look.
The complete check, without Terminal
Local Preflight runs every Microsoft rule, plus the 400-character path limit, against a Mac folder in Safari, Chrome or Firefox. Drag the folder onto the page and you get a list of every problem with its exact location and a suggested new name, exportable to Excel. File contents are never read or uploaded.
A simple order of work
- Delete what you don't need to move (old exports,
~$lock files). - Run the check and fix the blockers: those files won't transfer.
- Shorten the longest paths, especially if colleagues will sync the folder on Windows.
- Move the folder, then spot-check a few files in the browser and in the desktop apps.
Last reviewed 28 September 2026.