Playing with driver and DS installation I ended up with this in the server log:

10:54:11,424 ERROR [org.jboss.as.controller.management-operation] (management-handler-thread - 1) WFLYCTL0013: Operation ("add") failed - address: ([
    ("subsystem" => "datasources"),
    ("data-source" => "Postgres")
]) - failure description: {"WFLYCTL0080: Failed services" => {"org.wildfly.data-source.Postgres" => "WFLYJCA0033: Error during the deployment of Postgres
    Caused by: org.jboss.msc.service.StartException in anonymous service: WFLYJCA0032: Unable to start the ds because it generated more than one cf"}}

That was quite cryptic.

1) The 'ds' and 'cf' abbreviations should be replaced with full words. To me this is the minimum resolution of this issue.

2) If it is possible to make a reasonably likely guess at what would lead to this situation and provide that info in the message, that would be nice.

Context:

I tried deploying a JDBC driver and then adding a datasource using a CLI command:

data-source add --name=Postgres --driver-name=postgresql-42.2.18.jar --jndi-name=java:jboss/datasources/Postgres

The 3 params are the required ones. I wasn't surprised that wasn't sufficient and I understand that what's required beyond that can vary from driver to driver. But those are the required ones, so users experimenting with WildFly are liable to do what I did. (If any other params should be required, someone please file a separate issue.)

Adding a connection-url param allowed the command to work. If that param shouldn't be required, but not providing it is a likely cause of this problem, perhaps the WFLYJCA0032 message should note that as a hint?