If there is a too big of a difference in time between Amazon's S3 and the user's machine, S3 will error out with this message as it uses the webs standard Network Time Protocol for certain features.
For more context, Amazon syncs all timezones all over the world using its Amazon Time Sync Service. This service uses a fleet of satellite-connected and atomic reference clocks in each Region to deliver accurate current time readings of the Coordinated Universal Time (UTC) global standard through the Network Time Protocol (NTP).
In most cases, this error happens if you are uploading from for example Italy and your system clock is out of the sync with the Amazon Time set for that region (Italy).
Make sure your system time is set properly and you should not be having getting this issue in the future.