![How to Fix Mac Error icloud-sync-error — iCloud Sync Not Working [2026]](/images/blog/mac-error-icloud-sync-error-hero.webp)
Mac Error icloud-sync-error: iCloud Sync Not Working
Quick fix: Check Apple System Status — Go to apple.com/support/systemstatus. Full step-by-step below.
What Causes Mac Error icloud-sync-error?
Mac error icloud-sync-error (iCloud Sync Not Working) can be triggered by several issues:
- Apple iCloud servers experiencing an outage
- Incorrect system date and time causing authentication failure
- Corrupted CloudDocs cache folder preventing sync
- iCloud account signed out or authentication token expired
- Third-party security software blocking iCloud traffic
| Cause | Best fix |
|---|---|
| Apple iCloud servers experiencing an outage | Check Apple System Status |
| Incorrect system date and time causing authentication failure | Sign out and sign back in to iCloud |
| Corrupted CloudDocs cache folder preventing sync | Delete the CloudDocs cache |
| iCloud account signed out or authentication token expired | Fix system date and time |
| Third-party security software blocking iCloud traffic | Restart iCloud daemon via Terminal |
How to Fix Mac Error icloud-sync-error — Step by Step
Check Apple System Status
Go to apple.com/support/systemstatus. If iCloud Drive or any iCloud service shows an issue, wait for Apple to resolve it — nothing on your end will fix a server-side outage.
Sign out and sign back in to iCloud
System Settings > [your name] > Sign Out. Wait 30 seconds. Sign back in. This refreshes the authentication token that iCloud uses to verify your identity with Apple's servers.
Delete the CloudDocs cache
Quit all apps. Open Finder > Go > Go to Folder > type ~/Library/Application Support/CloudDocs. Move the session folder to Trash (do not empty yet). Restart your Mac. iCloud will rebuild this folder.
Fix system date and time
System Settings > General > Date and Time > enable Set time and date automatically. iCloud authentication uses time-based tokens — a clock that is off by more than a few minutes causes sync to fail silently.
Restart iCloud daemon via Terminal
Open Terminal:killall bird
The bird process manages iCloud Drive syncing. Restarting it forces a fresh sync attempt without rebooting your Mac.
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Frequently Asked Questions
Why does iCloud show as syncing but never finishes?
The sync is likely stuck on a large file, a file with a name conflict, or a file that is locked. Check Console app for iCloud errors, or look for a file with a cloud icon that never resolves in Finder.
Can I force iCloud to sync immediately?
Open Terminal and run brctl diagnose -s to trigger a sync. Also opening a Finder window in your iCloud Drive folder prompts the daemon to check for changes.
Will deleting the CloudDocs cache delete my files?
No. Your actual files are stored in iCloud's servers. The CloudDocs cache is a local sync database. Deleting it forces iCloud to rebuild the sync state — files re-download as you access them.
Why does iCloud sync work on iPhone but not Mac?
The iPhone and Mac use different sync implementations. The Mac uses the bird daemon which has its own cache. Issues on one do not necessarily reflect issues on the other.
How much storage does iCloud need?
Your iCloud storage must have room for all files you want to sync. Check: System Settings > [your name] > iCloud > Manage Account Storage. If it is nearly full, delete old backups or buy more storage.
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