Traceback (most recent call last):
  File "/usr/bin/do-release-upgrade", line 111, in <module>
    useProposed=options.proposed_release)
  File "/usr/lib/python3/dist-packages/UpdateManager/Core/MetaRelease.py", line 90, in __init__
    self.flavor_name = get_ubuntu_flavor_name()
  File "/usr/lib/python3/dist-packages/UpdateManager/Core/utils.py", line 447, in get_ubuntu_flavor_name
    pkg = get_ubuntu_flavor_package(cache=cache)
  File "/usr/lib/python3/dist-packages/UpdateManager/Core/utils.py", line 437, in get_ubuntu_flavor_package
    cache = apt.Cache()
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 105, in __init__
    self.open(progress)
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 162, in open
    progress.op = _("Building data structures")
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xfa in position 8: invalid