David Anderson on "[Plugin: UpdraftPlus - WordPress Backup and Restoration] S3 Error: Failed to upload: S3::putObject(): [417] Unexpected HTTP status"

Hi Stoan09,

It looks like your webserver is not directly connected to the Internet, but is behind a proxy server.

That's not a problem - the problem is that the proxy is broken.

You need to contact whoever runs your proxy server. Send them also this URL which has some related information:
http://stackoverflow.com/questions/5415849/amazons3-php-library-not-working-behind-squid

Best wishes,
David