Unfortunately, while the 500 is recorded in the nginx access log, there are no additional clues in the error log, and none in the php-fpm error log either, so I have no clues as to why this is failing.
I’ve checked with curl that I can successfully reach the endpoint, and that all seems fine.
Where else might I be able to find out more about why it’s failing?
I moved my MIAB backups from S3 Compatible to AWS S3 and saw these 500x errors. The 500x errors indicated to me that I was entering wrong information into MIAB. All the AWS backup needed was selecting right region (in your case Other), then key in S3 Host / Endpoint (no s3:// or https:// prefix!) , S3 Bucket & Path and credentials (less is more)
At the same time I hit the issue with duplicity v2 so no matter what I did the backups always timed out, so check duplicity is at v1.2. I was fiddling with this for a few days
As far as I can see I’ve set all the config the same as I did in the older post I linked to, which worked fine. This is really more about the problem of not reporting or logging errors than problems with backup - it’s fine for it to fail if I’ve got credentials wrong or something, but it needs to tell me that’s the problem.