Juju agent version

Juju offline mode.
when I am bootstrapping controller in offline mode, i am getting below error:

ERROR juju.cmd.juju.commands bootstrap.go:675 failed to bootstrap model: open url/juju-2.6.2-xenial-amd64.tgz: no such file or directory

Is there any juju agent with juju-2.6.2-xenial-amd64.tgz name ? i am getting something juju-2.6.2-ubuntu-amd64.tgz ?

Is it a bug for Juju?