Traceback (most recent call last):
  File "/usr/lib/ubuntu-release-upgrader/do-partial-upgrade", line 92, in <module>
    controller.doPartialUpgrade()
  File "/usr/lib/python3/dist-packages/DistUpgrade/DistUpgradeController.py", line 1837, in doPartialUpgrade
    if not self.askDistUpgrade():
  File "/usr/lib/python3/dist-packages/DistUpgrade/DistUpgradeController.py", line 1005, in askDistUpgrade
    self.cache.required_download)
  File "/usr/lib/python3/dist-packages/DistUpgrade/DistUpgradeViewGtk3.py", line 626, in confirmChanges
    demotions, downloadSize):
  File "/usr/lib/python3/dist-packages/DistUpgrade/DistUpgradeView.py", line 351, in confirmChanges
    assert(len(self.toInstall)+len(self.toUpgrade)+len(self.toRemove)+len(self.toRemoveAuto)+len(self.toDowngrade) == len(changes))
AssertionError