Unable to Sync to S3 with s3cmd

I’m running it through ROOT only.

Anyting other than this that you feel could be affecting the script usage?

Another issue now is setting up cron to automate the backup script.

While the commands are working with s3cmd tool when run one by one directly from command line, however when I created a .sh script, and trying to run through cron, the script runs fine but shows below error:

ERROR: S3 error: 400 (InvalidRequest): The authorization mechanism you have provided is not supported. Please use AWS4-HMAC-SHA256.

My .sh file is as follows:

#!/bin/sh
echo 'Started'
date +'%a %b %e %H:%M:$S %Z %Y'
s3cmd sync --recursive --preserve /srv s3://MyBucket
s3cmd sync --recursive --preserve /etc s3://MyBucket
s3cmd sync --recursive --preserve /home s3://MyBucket
s3cmd sync --recursive --preserve /var s3://MyBucket
dpkg --get-selections >> dpkg.list 2>&1
s3cmd sync --recursive --preserve dpkg.list s3://MyBucket
date +'%a %b %e %H:%M:$S %Z %Y'
echo 'Finished'

Any suggestions for this?