Adding OVHcloud OpenStack-based S3-compatible storage as a custom S3 storage in Plesk in Tools & Settings > Backup Manager > Remote Storage Settings > Amazon S3 Backup fails:
Unable to check bucket and directory existence. Make sure you are using correct IAM policy (400 Bad Request (Request-ID: tx2ef843a36acf491fb4b79-005df2411f)).
The error message stays the same despite what is set in the field Path - the bucket root or a directory inside the bucket.
Key and secret are created correctly according to the corresponding OVH article.
Accessing the bucket and working with it using AWS CLI works correctly.
The region for an custom S3-compatible endpoint is not specified in the file
Install the extension Panel.ini Editor (if it is not installed already).
Go to Extensions > My Extensions > Panel.ini Editor > Open > Editor.
Add the following lines into the end of the file:
RegionForCustomEndpoint = GRA
GRAwith the name of the region of your S3-compatible storage provider.
Click Save to save the changes.