Comment 2 for bug 1710436

You make mistake in container-format argument. As you can see in documentation - https://docs.openstack.org/image-guide/image-formats.html
Container format can be one of the following formats:
aki, ami, ari, bare, docker, ova, ovf.
Disk format can be raw or qcow2.

So, try command like this -
$ openstack image create --disk-format qcow2 --file Fedora-Cloud-Base-25-1.3.x86_64.qcow2 Fedora-Cloud-Base-25-1.3.x86_64.qcow2