Traceback (most recent call last):
  File "/tmp/ubuntu-release-upgrader-xcftkgja/groovy", line 8, in <module>
    sys.exit(main())
  File "/tmp/ubuntu-release-upgrader-xcftkgja/DistUpgrade/DistUpgradeMain.py", line 238, in main
    if app.run():
  File "/tmp/ubuntu-release-upgrader-xcftkgja/DistUpgrade/DistUpgradeController.py", line 2089, in run
    return self.fullUpgrade()
  File "/tmp/ubuntu-release-upgrader-xcftkgja/DistUpgrade/DistUpgradeController.py", line 2048, in fullUpgrade
    if not self.calcDistUpgrade():
  File "/tmp/ubuntu-release-upgrader-xcftkgja/DistUpgrade/DistUpgradeController.py", line 1118, in calcDistUpgrade
    if not self.cache.installTasks(self.tasks):
AttributeError: 'DistUpgradeController' object has no attribute 'tasks'