Amazon S3 not authorized iam:GetUser

I have struck a problem setting up a Duplicati backup to Amazon S3 from Windows. I have setup the AWS User and Bucket in similar fashion to other working configs. However, when clicking “Test Connection” on the Duplicati Backup Destination form I am confronted with the error:
"User: arn:aws:iam::XXXXXXXXXXXX:user/ABC is not authorized to perform: iam::GetUser on resource: user ABC

My working Duplicati/Amazon configs are all on Ubuntu laptops and this is the first time I have attempted to configure a Duplicati/Amazon backup from a Windows laptop.

Curiously, “Test Connection” is successful with this User and Bucket from a Ubuntu laptop, but generates the error when configured on a Windows laptop.

I note that on Windows (not Ubuntu) the Duplicati Backup Destination Form includes an “Client Library to Use” but neither option (Amazon AWS SDK | Minio SDK) resolves the error.

Windows 10 Home
Duplicati - 2.0.5.1_beta_2020-01-18

I would be grateful to know how to resolve this issue! Thanks in advance…

I was able to replicate this error on Ubuntu with Duplicati - 2.0.5.1_beta_2020-01-18

I was also able to resolve this issue on both Windows and Ubuntu by reverting to Duplicati - 2.0.4.23_beta_2019-07-14

Hence it would appear that this error relates to Duplicati - 2.0.5.1_beta_2020-01-18

I encountered the same issue on two different (Windows) machines. One was an upgrade from the previous Duplicati version, the other had a fresh Duplicati installation. The two machines used to different S3 buckets, which were configured similarly, though.

The good news: the error message affected the connection test only. Once I ignored it and continued configuring the connection, the actual backup process ran smoothly.

Thank you Helge. I have confirmed that the current Duplicati version does indeed work on my Ubuntu setup (despite reporting a failed connection test).