$ juju models
Controller: mycontroller
Model Cloud/Region Status Machines Cores Access Last connection
admin/default aws/eu-central-1 available 3 3 admin never connected
$ juju --debug switch mycontroller:default
10:44:33 INFO juju.cmd supercommand.go:63 running juju [2.1.0 gc go1.6.2]
10:44:33 DEBUG juju.cmd supercommand.go:64 args: []string{"juju", "--debug", "switch", "mycontroller:default"}
10:44:33 INFO juju.juju api.go:72 connecting to API addresses: [(controller-ip):17070 (controller-private-ip):17070]
10:44:33 DEBUG juju.api apiclient.go:590 dialing "wss://(controller-ip):17070/api"
10:44:33 DEBUG juju.api apiclient.go:590 dialing "wss://(controller-private-ip):17070/api"
10:44:33 DEBUG juju.api apiclient.go:593 successfully dialed "wss://(controller-ip):17070/api"
10:44:33 INFO juju.api apiclient.go:521 connection established to "wss://(controller-ip):17070/api"
10:44:33 DEBUG juju.juju api.go:258 API hostnames [(controller-ip):17070 (controller-private-ip):17070] - resolving hostnames
10:44:33 DEBUG juju.juju api.go:284 API addresses unchanged
10:44:33 ERROR cmd supercommand.go:458 "mycontroller:default" is not the name of a model or controller
10:44:33 DEBUG cmd supercommand.go:459 (error details: [{github.com/juju/juju/cmd/juju/commands/switch.go:178: "mycontroller:default" is not the name of a model or controller}])