According to AWS documentation:

Any new regions after January 30, 2014 will support only Signature Version 4 and therefore all requests to those regions must be made with Signature Version 4.

Phabricator only support signature version 2 (https://github.com/phacility/phabricator/blob/master/externals/s3/S3.php#L1820-L1823), so when we upload file to S3 will get error like this: