Creating this thread off the details of THIS thread. Topic wasn't accurate, wanted to bring more attention to a thread outlined with the actual issue in Subject line.
Problem is related to Duplicati and it's underlying Mono install being able to properly import the right root certificates to trust for SSL communications. The problem, that I've encountered, is continually having my backups error out or fail to start, due to a certificate mismatch on the server side. Knowing Amazon likely changes front end servers for CloudDrive, the cert hashes keep changing. The main problem being, that the top level root isn't trusted, so it's looking for some sort of validation that it's ok to trust these lower sub certs due to the chain not having a trusted root. (I Believe that's the issue at least)
@ryecoaaron has been nice enough to help troubleshoot by making adjustments to the plugin to test out various workaround or resolutions. The first was adding in the mozroots solution as outlined by many to solve this in a normal Debian based installation. That didn't seem to do the trick. After this, he altered to include the other suggested workaround of adding an Environment Variable to specify MONO_TLS_PROVIDER=legacy. At first, I thought this seemed to work, but no luck after running for awhile, I returned to the same error again.
Any ideas folks have? Has anyone been able to successfully get Duplicati running on other systems with the same issue? What was done to fix/work around this issue? Any other alternatives to what can be done to the OMV plugin to adjust/account for scenarios outside of the Debian standard install?