We need to see the actual error. I’m guessing maybe there’s a difference of opinion about the hostname of the user logging in, maybe? I don’t really know much about how users and permissions and authentication work in PostgreSQL.
I am also able to login to virtualmin as upmanager and edit/manage postgresql database upmanager; But not in my Mojolicious app.
I think it has much to do with user/database/table/host permissions with PostgreSQL which you also alluded to. I hope someone with deeper PostgreSQL knowledge would help me with it.
I am asking it here because I am trying it on Centos8 with Virtualmin ( same source code works just fine in the Raspberry Pi).