I have searched on the web for over two days now, and probably have looked through most of the online documented scenarios and workarounds, but nothing worked for me so far.
I had a similar error, but for me it seemed to be caused by re-using an IAM user to work with S3 in two different Elastic Beanstalk environments. I treated the symptom by creating an identically permissioned IAM user for each environment and that made the error go away.