AWS S3 upload fails: RequestTimeTooSkewed

The time verification happens at the start of your upload to S3, so it won't be to do with files taking too long to upload.

Try comparing your system time with what S3 is reporting and see if there is any unnecessary time drift, just to make sure:

# Time from Amazon
$ curl http://s3.amazonaws.com -v

# Time on your local machine
$ date -u

(Time is returned in UTC)

Amazon S3 uses NTP for its system clocks, to sync with your clock. Run

sudo apt-get install ntp

then open /etc/ntp.conf and add at the bottom

server 0.amazon.pool.ntp.org iburst
server 1.amazon.pool.ntp.org iburst
server 2.amazon.pool.ntp.org iburst
server 3.amazon.pool.ntp.org iburst

Then run

sudo service ntp restart

I was running aws s3 cp inside docker container on a MacBook Pro and got this error. Restart the Docker for Mac fixed this issue.