unRAID ownCloud WebDav error connecting - can't connect SSL

I’m trying to connect to an ownCloud server running in a Docker on unRAID for my backups. Each time I try to connect, I get this error:

Failed to connect: The server certificate had the error RemoteCertificateChainErrors and the hash SOMELONGHASHINHEXADECIMAL If you trust this certificate, use the commandline option --accept-specified-ssl-hash=SOMELONGHASHINHEXADECIMAL to accept the server certificate anyway. You can also attempt to import the server certificate into your operating systems trust pool. You may want to import a set of trusted certificates into the Mono certificate store. Use the command: cert-sync /etc/ssl/certs/ca-certificates.crt #for Debian based systems cert-sync /etc/pki/tls/certs/ca-bundle.crt #for RedHat derivatives Read more: Release Notes Mono 3.12.0 | Mono

(I’ve changed the has to the text: SOMELONGHASHINHEXADECIMAL)

Any idea what I do to fix this?

It depends on what kind of SSL certificate you are using.

If the SSL certificate is signed by a valid certificate authority, you need to update the Mono certificate store. There is a guide here: SSL TLS support in Mono · duplicati/duplicati Wiki · GitHub

If you are using a self-signed SSL certificate, you can add the option as suggested.
But I would recommend getting a free certificate from LetsEncrypt:

For what it’s worth, I’m in a very similar boat but I went Crashplan -> unRAID+NextCloud and I can confirm the “–accept-specified-ssl-has=xxxxxxxx” option worked for me.