Exporting AMI to S3 and restore it to see if it works

I have anAMI Ubuntu 18.04, upgraded from 16.04. The kernel version 4.15.0. I have been trying to export it to s3 and have been getting an s3 error on permissions even if I make the s3 bucket public . Need someone who can help me do this for me and provide a writeup of reproducible steps to do this. This is the error I am getting Here is the error

An error occurred (InvalidParameter) when calling the ExportImage operation: Access denied to the bucket newimage123