I’m having trouble with AlienSync after installing the app and software on my device. It won’t sync properly, and some features are not working the way they should. I need help figuring out what went wrong and how to fix it so I can get everything running again.
Start with the boring stuff first.
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Check version match.
If the AlienSync app and the desktop software are on different versions, sync fails a lot. Open both, check About or Settings, and update both sides. -
Sign out, then sign back in.
Bad auth tokens break sync more often than people think. Log out on every device. Reboot. Log back in. -
Check permissions.
AlienSync usually needs file access, background activity, local network, and notifications. If one permission got blocked during install, parts of the app act weird. On Android, look at App Permissions and battery optimization. On iPhone, check Background App Refresh. On Windows or Mac, check firewall and folder access. -
Same network test.
Put both devices on the same Wi-Fi and try a small sync, like one folder or 2 to 3 files. If that works, the issue is often firewall, VPN, or router isolation. -
Turn off VPN, antivirus web shield, and firewall tempraorily.
A lot of sync apps choke on packet inspection. If sync starts working with those off, you found the culprit. -
Clear cache.
If AlienSync has an option like Clear Cache, Reset Sync Database, or Rebuild Index, use it. Corrupt indexes cause missing files and broken features. -
Check storage.
Low disk space breaks sync and thumbnails and previews. Keep at least 10 percent free on both devices. -
Reinstall cleanly.
Uninstall app and software. Delete leftover AlienSync folders in AppData, Library, or Android data if they remain. Then reinstall the latest build.
If none of this fixes it, post your device model, OS version, AlienSync version, and exact error msg. Without that, people are guessing tbh.
A couple things to check that are different from what @sterrenkijker already listed.
First, make sure your system clock is correct on every device. Sounds dumb, but bad date/time settings can break login sessions, cloud checks, and sync validation. I’ve seen apps act half-broken just because Windows time drifted a few mins.
Second, test with a brand new sync folder instead of your real one. Make an empty folder, drop in one text file, and point AlienSync at that. If the test folder works but your normal folder does not, the problem is probably path length, weird filename characters, locked files, or permissions inherited from the original folder.
Also check where the folder is located. If you’re trying to sync something inside Desktop, Documents, iCloud Drive, OneDrive, Dropbox, or a network share, that can cause conflicts. Put the sync folder somewhere simple like C:\AlienSyncTest or a plain folder in Home on Mac and see if behavior changes. Cloud-on-top-of-cloud setups get messy fast.
I actually kinda disagree with doing a full reinstall too early. Reinstalls look productive, but if the issue is a bad folder target or another sync tool fighting AlienSync, you just waste time redoing setup.
One more thing: open Task Manager or Activity Monitor and see if the AlienSync background service/helper is actually running. Sometimes the app opens but the sync service crashed silently, so the UI loads while features don’t. If there’s a logs section, check timestamps and error wording. That stuff matters way more than “it doesnt work.”
Post the exact device, OS, where your sync folder lives, and whether another cloud app is touching the same files. That usually narrows it down fast.