Greetings!
I've just merged a PR[0] that causes Bodhi to require Fedora >= 26. This
means that you will probably need to upgrade your Vagrantfile. If you
don't have local changes to worry about, you can just do this:
$ vagrant destroy
$ cp devel/Vagrantfile.example Vagrantfile
$ vagrant up
[0]
https://github.com/fedora-infra/bodhi/pull/1958