My Firefox sync worked on Windows (Win 7) last night, But I was trying to make it work on Linux (Ubuntu Mate) and Android (5.1.1) for hours and nothing works. Windows and Linux are both on same Laptop. I tried Removing config folder, Deleting my Firefox account and Recreating it a dozen times but still doesn't work. Windows did fine (At least the last time I tried it, which was last night !), But I was busy trying to make it work on Linux and Android since then. It acts different on both : I'm really confused because this was working before. Yesterday I decided to Reinstall my Operating Systems and it happened after I did so. I only Reinstalled my Linux and Windows so if there's anything wrong with Operating Systems, It should work on Android ! All my Firefox versions are the Latest (49.0 until today), So there shouldn't be an Old version bug or something ! Linux : When I log into my account it asks for EMail verification and when I verify my Email (Either on the same browser or on my Android browser), Firefox on Linux says "Verification complete, Sync will begin momentarily" but the Top-Right menu where I can sync Manually is still waiting for Sync. After I Restart Firefox, manual Sync icon appears, But when I click on the Icon, Literally 'Nothing' happens. The icon won't start Spinning (As it should normally do !). I even checked about:sync-log, There's nothing there (Both with (true) and without (false) logOnSuccess config). Android : When I log into my account and verify my EMail everything works fine but nothing syncs. So I try the Manual Sync button and when I push it Firefox starts syncing but then No matter how long I wait, It won't sync and if I get out of Firefox even momentarily and return the "Syncing ..." is turned to Sync button again with "Last sync : never". What I'm suspicious towards is Firefox boycotting Iran (Where I live), But I never saw that before ! I mean Firefox believes in free software movement, Yeah ? Unless it's servers are located in USA and they are forcing them to do so, Which I don't know about ? Does anyone know ? By the way, if you need any more information to solve this problem, I'm pleased to give.