"Time difference" error

Sometimes your desktop client shows "Invalid Time" error at the bottom of the Sync Main View:

or a warning for a certain share:

clicking on which will show the "Time difference" warning for one or several peers

listed when clicking on the warning:

Your mobile devices will show only empty list instead of files. The error appears when one of your peer's internal clock (or timezone settings) is set incorrectly. Each time Sync decides which file is newer, it compares files modification time. First - it converts it to GMT (as Sync might work across the world), then compares it.

Sync also converts peers' local time, time zone taken into account, to GMT. So if any peer has invalid time (or, which is more often - invalid TimeZone) - the time difference becomes more than 600 seconds allowed, and Sync gives the warning.

There are 2 ways to resolve the issue:
A) check that your Time Zone setting is correct on all devices (just set correct time for your current time zone if you travel).

You may check the UTC time on all devices with the following command:
Android/Mac/Linux in Terminal:

date -u (for Android you may use any Terminal from Google Play).

Windows (in Command Prompt) 

for /f %x in ('wmic path win32_utctime get /format:list ^| findstr "="') do set %x

Result shall be the same on all peers. Better check it with minimal time lag t have more accurate results for comparing.

B) make it automatic.

Setting automatic time
For iOS:

1. Open Settings.
2. Tap General > Date & Time.
3. Set Automatically (Set to ON).

Android:

1. Open Settings.
2. In the System section, tap Date & time
3. Make sure "Automatic date and time" and "Automatic time zone" checked.

Windows Phone:

1. Open settings.
2. Tap Date + Time.
3. Make sure that switch "Automatic" is set to "On".

Mac OS X

1. Click apple menu.
2. See "Date & Time" and "Time Zone" tabs, both contain "Set automatic" checkbox.

Windows

1. Right-click the watch on your system tray, choose "Adjust date & time".
2. <Click "Internet time" tab, sync time with internet.
3. Click "Date & Time" tab, adjust Time Zone manually.

Linux

1. Not all Linux distros support automatic timezones, so you can adjust it manually.
2. Find file /etc/localtime. Remove it and make a new symlink to /usr/share/zoneinfo to the file representing your city.

Once time is adjusted, restart Sync.