Dropbox Smart Sync Not Working

Smart Sync allows you to view and access files in your Dropbox folder without downloading them to your hard drive, saving physical disk space. When Smart Sync fails, “online-only” files will still occupy storage space, the right-click “Make online-only” option may be missing, or opening online-only files will result in system crashes or file load errors.

This guide details how to re-register the system-level syncing drivers and repair integration extensions on both Windows and macOS.

1. Primary Causes of Smart Sync Failures

Smart Sync relies heavily on operating system integrations:

• Disabled Windows Cloud Files Driver (cldflt): Windows uses the cldflt.sys kernel driver to coordinate cloud storage placeholders. If this service is disabled, Smart Sync ceases to function.
• Disabled macOS FileProvider Extension: On macOS, Dropbox uses a Apple-designed extension to manage virtual folders. If this plug-in is disabled or blocked in system settings, context menu items disappear.
• Incorrect File Permissions: If the sync client cannot modify file metadata, it cannot mark files as online-only or download them on demand.

A. Enable and Start the cldflt Driver

1. Search for PowerShell in the Start Menu, right-click, and select Run as Administrator.
2. Run this command block to verify, configure, and start the system driver:

   # Check current status of the Cloud Files Filter driver
   $service = Get-Service -Name cldflt -ErrorAction SilentlyContinue
   
   if ($service) {
       Write-Host "Current cldflt Status: $($service.Status)" -ForegroundColor Cyan
       
       # Set service startup type to Automatic
       Set-Service -Name cldflt -StartupType Automatic
       
       # Start the service if it is stopped
       if ($service.Status -ne 'Running') {
           Start-Service -Name cldflt
           Write-Host "Success! Cloud Files Filter driver has been started." -ForegroundColor Green
       } else {
           Write-Host "Driver is already running." -ForegroundColor Green
       }
   } else {
       Write-Host "Error: cldflt driver service not found on this Windows installation." -ForegroundColor Red
   }

:: Kill and restart explorer.exe
taskkill /f /im explorer.exe
start explorer.exe

A. Re-register and Force Load the Dropbox Extension

1. Open Terminal (via Cmd + Space, type Terminal).
2. Run these commands to reset and enable the plug-in:

   # Disable and ignore the extension temporarily
   pluginkit -e ignore -i com.getdropbox.dropbox.garcon 2>/dev/null || true
   
   # Force-enable and use the extension
   pluginkit -e use -i com.getdropbox.dropbox.garcon
   
   # Verify that the extension is active (should display a '+' next to it)
   pluginkit -m -i com.getdropbox.dropbox.garcon
   
   # Force relaunch Finder to load the extension
   killall Finder

B. Approve extensions in System Settings

Ensure macOS is not blocking the extensions:

1. Go to System Settings > Privacy & Security > Extensions.
2. Click Added extensions (or Finder extensions).
3. Ensure the checkbox next to Dropbox is enabled.

4. Verify Actual vs. Logical Disk Space

Sometimes users believe Smart Sync is not working because the “Size” of a file matches its actual size.

• Size: Represents the logical size (e.g., a 10 GB video file).
• Size on disk: Represents the physical size occupied on your drive. For online-only files, this should read 0 bytes (or a few kilobytes for NTFS/APFS metadata blocks). Verify the “Size on disk” parameter in the file properties menu (Windows) or “Get Info” panel (macOS).

5. Summary Quick Reference Checklist