How to Fix Mac Sync Client Cannot Open SharePoint Files

When you use the OneDrive sync client on a Mac, you may see an error that SharePoint files will not open or the sync client fails to start. This problem often occurs after a macOS update, a change in network settings, or a corrupted sync cache. The root cause is either a blocked sync process, outdated credentials, or a damaged local sync database. This article explains why the sync client cannot open SharePoint files on Mac and provides step-by-step fixes to restore normal file access.

Why the OneDrive Sync Client on Mac Cannot Open SharePoint Files

The OneDrive sync client on macOS uses a background process called OneDrive.app to synchronize files between your local machine and SharePoint document libraries. When this process is blocked or its data becomes corrupted, files appear as placeholders or fail to open with an error message such as “Cannot open the file” or “The file is locked.” Three common causes trigger this failure:

Outdated or Revoked Authentication Tokens

Microsoft 365 requires periodic reauthentication. If your token expires or is revoked due to a password reset or multi-factor authentication change, the sync client loses permission to download or open files. The client may still show the file list but cannot retrieve the actual content.

Corrupted Sync Cache Database

The sync client stores metadata and partial file data in a local database located at ~/Library/Application Support/OneDrive. After a macOS update or an abrupt shutdown, this database can become corrupted. The client then hangs or reports that files cannot be opened, even though the files exist on the server.

System Permission Restrictions in macOS

Starting with macOS Catalina, Apple requires apps to request explicit permission to access certain folders. If OneDrive does not have Full Disk Access or Files and Folders permission, it cannot read or write to the SharePoint sync folders. The error appears as a generic “file cannot be opened” message.

Steps to Fix the OneDrive Sync Client on Mac

Perform the following steps in order. Test file access after each step to see if the issue is resolved.

1. Quit and Restart OneDrive
   Click the OneDrive cloud icon in the menu bar. Select Quit OneDrive. Wait 10 seconds, then open OneDrive from the Applications folder. This clears temporary glitches.
2. Unlink and Relink Your Account
   Click the OneDrive cloud icon > Preferences > Account > Unlink this Mac. Confirm the action. Sign back in with your Microsoft 365 work or school account. This forces a fresh authentication token.
3. Clear the Sync Cache
   Quit OneDrive completely. Open Finder and press Command+Shift+G. Type ~/Library/Application Support/OneDrive and press Enter. Delete all files and folders inside this directory. Do not delete the folder itself. Restart OneDrive. The client will rebuild the database from the server.
4. Grant OneDrive Full Disk Access
   Open System Preferences > Security & Privacy > Privacy tab. Select Full Disk Access from the left pane. Click the lock icon to make changes. Click the plus (+) button and add OneDrive from the Applications folder. Restart OneDrive.
5. Reset the OneDrive App
   If the problem persists, reset the app. Quit OneDrive. Open Terminal from Applications > Utilities. Run this command:
   killall OneDrive
   Then run:
   ~/Library/Application Support/OneDrive/OneDrive.app/Contents/MacOS/OneDrive
   This starts the app in reset mode. Follow the on-screen prompts to set up sync again.

If OneDrive Still Cannot Open SharePoint Files After the Main Fix

Some issues require additional steps beyond the standard reset. Below are the most common remaining failure patterns and their specific fixes.

SharePoint Files Show as Grayed Out or Unavailable

This symptom usually means the sync client is stuck in a paused state. Click the OneDrive cloud icon and check if Pause syncing is active. If so, click Resume syncing. If the option is not visible, go to Preferences > Network and increase the upload and download rate limit to at least 50% of your bandwidth.

OneDrive App Will Not Launch After macOS Update

macOS updates sometimes remove OneDrive from the login items list. Open System Preferences > Users & Groups > Login Items. Click the plus button and add OneDrive. Restart your Mac. This ensures the sync client starts automatically and completes its initialization.

Permission Denied Error When Opening a Synced File

The file may have been checked out by another user or have restrictive sharing permissions. Open the file in a browser by navigating to the SharePoint document library. Check the file’s properties for a check-out status. If checked out, ask the user to check it back in. If the file is not checked out, verify that you have at least Contribute permissions on the library.

OneDrive Sync Client vs Browser Access for SharePoint Files

Item	OneDrive Sync Client	Browser (SharePoint Online)
File access method	Local file system via Finder	Web browser URL
Offline availability	Files-on-Demand or downloaded copies	None unless file is downloaded manually
File locking behavior	Sync client respects check-out status	Opens in browser with read-only if locked
Authentication refresh	Requires relink after token expiry	Uses browser session cookies
Best for	Frequent editing of many files	One-time viewing or occasional editing

After completing the steps above, you should be able to open SharePoint files through the OneDrive sync client on your Mac. If the problem continues, use the browser as a temporary workaround while Microsoft Support investigates. For persistent issues, run the Reset OneDrive command in Terminal to force a full reinitialization of the sync engine.