Traceback (most recent call last):
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquity/server/controllers/mirror.py", line 275, in run_mirror_selection_or_fallback
    await self.find_and_elect_candidate_mirror(context=context)
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquity/server/controllers/mirror.py", line 226, in find_and_elect_candidate_mirror
    raise NoUsableMirrorError
subiquity.server.controllers.mirror.NoUsableMirrorError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquity/server/controllers/install.py", line 636, in install
    for_install_path = "cp://" + await self.configure_apt(context=context)
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquitycore/context.py", line 149, in decorated_async
    return await meth(self, **kw)
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquity/server/controllers/install.py", line 171, in configure_apt
    configurer = await mirror.wait_config(fsc._info.name)
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquity/server/controllers/mirror.py", line 349, in wait_config
    await self._promote_mirror()
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquity/server/controllers/mirror.py", line 328, in _promote_mirror
    await self.run_mirror_selection_or_fallback(self.context)
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquity/server/controllers/mirror.py", line 277, in run_mirror_selection_or_fallback
    await self.apply_fallback()
  File "/snap/hostname-desktop-installer/1243/bin/subiquity/subiquity/server/controllers/mirror.py", line 240, in apply_fallback
    raise RuntimeError("aborting install since no mirror is usable")
RuntimeError: aborting install since no mirror is usable