Comment 1 for bug 1878481

It seems you have a proper [neutron] and [placement] section in your nova.conf but you don't have a [cinder] section. You need to configure the similar [cinder] section to allow nova to talk to cinder. I think this is the root case of the error you see:

ClientException: Unexpected API Error. Please report this at http://bugs.launchpad.net/nova/ and attach the Nova API log if possible.
<class 'cinderclient.exceptions.Unauthorized'> (HTTP 500)

I'm setting this bug to Invalid now. Please fix you config and try again. If you still see the same issue then set the bug status back to New and add your new config to the report.