general

Sync Icons Explained

Resolution Checklist

  • 1 Understand Sync Icon Meanings
  • 2 Fix Missing Sync Icons on Windows (Registry Overlay Limits)
  • 3 Fix Sync Extensions on macOS Finder
  • 4 Resolve Stalled Sync Overlay Indicators
  • 5 Summary Quick Reference Checklist

Sync Icons Explained

Sync icons are icon overlays added to files and folders in Windows Explorer and macOS Finder. They provide real-time status of your cloud storage sync states (e.g., whether a file is online-only, pinned locally, syncing, or blocked by a permissions error). If these overlays disappear, you lose visibility into whether your data is backed up.

This guide explains what each standard sync icon means and details how to fix broken or missing sync overlays on both Windows and macOS.

1. Understand Sync Icon Meanings

Most major cloud storage providers (OneDrive, Google Drive, Dropbox, iCloud) use standard symbols:

  • Blue Cloud Outline: Online-only. The file exists on the cloud server but takes up 0 bytes on your computer. Double-clicking it downloads the file on-demand.
  • Green Circle with Checkmark (White Center): Locally Cached. You have opened the file and it has downloaded to your hard drive. If you need local disk space, you can right-click it and select “Free up space” to revert it to a cloud placeholder.
  • Solid Green Circle with White Checkmark: Always Keep on Device (Pinned). You have selected “Always keep on this device”. The file is downloaded permanently and remains offline-ready.
  • Two Circular Arrows (Blue/Green): Syncing. The file is currently uploading or downloading.
  • Red Circle with White ‘X’: Sync Error. The file cannot sync due to a naming conflict, file lock, size limit, or permissions issue.
  • Gray Cloud with Slash / Slash Over Logo: Disconnected/Paused. The client application is paused, logged out, or has no internet connection.

2. Fix Missing Sync Icons on Windows (Registry Overlay Limits)

Windows has a hard limit of 15 Shell Icon Overlay slots in the Registry. Windows reserves some for system overlays, leaving about 11. If you install multiple cloud apps (OneDrive, Dropbox, Google Drive, Box), they compete for these slots. The apps that start with spaces in their Registry names get priority, pushing others out.

Reset Shell Icon Overlay Registry Priority

  1. Press Win + R, type regedit, and press Enter to open the Registry Editor.
  2. Navigate to the following path: 
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers
  3. You will see a list of subkeys. The folders at the top of the list get priority. Cloud clients prefix their names with spaces (e.g., OneDrive1, DropboxExt1) to force themselves to the top.
  4. If your preferred client’s icons are missing (e.g. OneDrive), rename other unused entries (like old tortoisesvn or box keys) by prefixing them with a z_ so they sort to the bottom.
  5. Exit Registry Editor.
  6. Open Task Manager (Ctrl + Shift + Esc), scroll to the bottom, select Windows Explorer, and click Restart.

3. Fix Sync Extensions on macOS Finder

On macOS, sync icons are driven by Finder Extensions under the Apple FileProvider framework. If they go missing, you must enable them in System Settings or restart the Finder API.

A. Enable Finder Extensions in macOS System Settings

  1. Open System Settings > Privacy & Security > Extensions.
  2. Click on Finder or Added Extensions.
  3. Locate your cloud client (e.g., “Dropbox Finder Integration” or “Google Drive”) and ensure the checkbox is checked ON.

B. Force Kill and Reload macOS Finder

Restart Finder to reload the active plist properties and extension injections:

  1. Open Terminal (via Spotlight).
  2. Run: 
    # Restart Finder to reload icon overlays
killall Finder

4. Resolve Stalled Sync Overlay Indicators

If a folder’s icon is stuck displaying the “Syncing” arrows indefinitely, but no files inside are uploading:

A. Flush File System Notification Buffer (Windows Command Prompt)

Run as administrator to clear file indexers:

:: Reset folder indexer components
ie4uinit.exe -show
taskkill /f /im explorer.exe
start explorer.exe

B. Reset the Cloud Client Cache to Trigger Overlay Update

If the overlay engine has lost sync with the database:

  • OneDrive: Run %localappdata%\Microsoft\OneDrive\onedrive.exe /reset
  • Google Drive: Toggle the application offline in Settings, wait 10 seconds, and toggle it back online.

5. Summary Quick Reference Checklist

Action TargetOperating SystemTerminal Command / PathExpected Outcome
Check Registry KeysWindowsregedit > ShellIconOverlayIdentifiersVerifies priority slots for icon overlays.
Restart ExplorerWindowsTask Manager > Windows Explorer > RestartApplies Registry overlay sorting changes.
Enable ExtensionmacOSSystem Settings > Privacy & Security > ExtensionsGrants permission to overlay Finder icons.
Relaunch FindermacOSkillall FinderReloads macOS Finder and displays active overlays.
Clear Stuck IconsWindowsie4uinit.exe -showClears system icon cache database.
Reset Sync ClientWindows/macOSClient PreferencesSyncs client database metrics to reset stuck overlays.