AWS S3 bucket location eu-central-1 not supported

Virtualmin fails to store backups in an AWS S3 bucket, if bucket location is eu-central-1 (Frankfurt/Germany).

This is possibly due to the fact that this is the first region that requires AWS Signature Version 4 of authenticating requests (all other regions also support version 2), see links at the end of this article.

Backup failed! See the progress output above for the reason why.
Total backup time was 02 minutes, 48 seconds.

Virtual servers that failed :
Sent by Virtualmin at:

Creating backup for virtual server virtualmin-domain ..
    Copying virtual server configuration ..
    .. done

    Backing up Cron jobs ..
    .. none defined.

    Saving mail aliases ..
    .. done

    Saving mail and FTP users ..
    .. done

    Backing up mail and FTP user Cron jobs ..
    .. none to backup

    Backing up Dovecot control files ..
    .. none found

    Creating TAR file of home directory ..
    .. done

    Uploading archive to Amazon's S3 service ..
    .. upload failed! Invalid HTTP response : HTTP/1.1 400 Bad Request

.. completed in 1 minutes, 45 seconds

AWS Signature Version 4:

Amazon S3 supports Signature Version 4, a protocol for authenticating inbound API requests to AWS services, in all AWS regions. At this time, existing AWS regions continue to support the previous protocol, Signature Version 2. 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.

Note: AWS officially announced the eu-central-1 region on 23 October 2014.

The AWS4 authorization mechanism requires AWS4-HMAC-SHA256:



That's correct - the solution is to install the aws command provided by Amazon which supports the new authentication system used in eu-central-1 . You can get it from

Is this likely to be taken care of within Virtualmin&Webmin and time in the near future? Or will it always require the AWS CLI to be installed manually? Once installed will the Virtualmin backups work again or do they have to be manually run/created?

We recommend installing the aws command if you can, as it's always going to be more reliable than relying on Virtualmin's implementation of Amazon's API.

This is also required if using EU (London).

Easily done with yum install awscli (CentOS)

HI, thanks, you've saved my night !!!!! Works great with aws client, doesn't at all without.