Starting from Juju 2.9.29, the support for empty network space name ("") has been dropped. Currently, in the openstack base bundle, the openstack-base-virt-overlay.yaml in both stable [1] and development [2] directories are using empty empty network space names. When deploying a bundle with one of these overlay files, the following error is produced:
```
ERROR cannot deploy bundle: space "" not found
```
To resolve this question, we can either remove these bindings sections all together, or explicitly pass in the actual space name ("alpha" by default).
[1] https://github.com/openstack-charmers/openstack-bundles/blob/master/stable/overlays/openstack-base-virt-overlay.yaml
[2] https://github.com/openstack-charmers/openstack-bundles/blob/master/development/overlays/openstack-base-virt-overlay.yaml
It certainly seems like Juju have changed their behaviour on a patch release. Setting to triaged/medium.