This just happened to me on the amd64 architecture.
One package failed to upgrade (the package whoopsie).
This is the current python trace:



root@rivendell:/home/nazgul# update-manager -c -d
Neue Veröffentlichungen von Ubuntu werden gesucht
»vivid.tar.gz« wird gegenüber »vivid.tar.gz.gpg« legitimiert 
»vivid.tar.gz« wird entpackt
No candidate ver:  libharfbuzz0:i386
No candidate ver:  librtmp0
No candidate ver:  libharfbuzz0:i386
No candidate ver:  librtmp0
No candidate ver:  linux-image-3.16.0-23-generic
No candidate ver:  linux-image-extra-3.16.0-23-generic
Traceback (most recent call last):
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeController.py", line 1137, in doDistUpgrade
    res = self.cache.commit(fprogress,iprogress)
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeCache.py", line 267, in commit
    apt.Cache.commit(self, fprogress, iprogress)
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 505, in commit
    raise SystemError("installArchives() failed")
SystemError: installArchives() failed

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/vivid", line 8, in <module>
    sys.exit(main())
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeMain.py", line 240, in main
    if app.run():
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeController.py", line 1831, in run
    return self.fullUpgrade()
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeController.py", line 1796, in fullUpgrade
    if not self.doDistUpgrade():
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeController.py", line 1182, in doDistUpgrade
    self._view.getTerminal().call(cmd)
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeViewGtk3.py", line 377, in call
    (success, pid) = self.term.spawn_sync(Vte.PtyFlags.DEFAULT,
AttributeError: 'Terminal' object has no attribute 'spawn_sync'
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 102, in apport_excepthook
    pr.add_proc_info(extraenv=['PYTHONPATH', 'PYTHONHOME'])
  File "/usr/lib/python3/dist-packages/apport/report.py", line 521, in add_proc_info
    raise ValueError('%s does not exist' % self['ExecutablePath'])
ValueError: /usr/bin/python3.4 (deleted) does not exist

Original exception was:
Traceback (most recent call last):
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeController.py", line 1137, in doDistUpgrade
    res = self.cache.commit(fprogress,iprogress)
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeCache.py", line 267, in commit
    apt.Cache.commit(self, fprogress, iprogress)
  File "/usr/lib/python3/dist-packages/apt/cache.py", line 505, in commit
    raise SystemError("installArchives() failed")
SystemError: installArchives() failed

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/vivid", line 8, in <module>
    sys.exit(main())
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeMain.py", line 240, in main
    if app.run():
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeController.py", line 1831, in run
    return self.fullUpgrade()
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeController.py", line 1796, in fullUpgrade
    if not self.doDistUpgrade():
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeController.py", line 1182, in doDistUpgrade
    self._view.getTerminal().call(cmd)
  File "/tmp/ubuntu-release-upgrader-1wmkhnt8/DistUpgrade/DistUpgradeViewGtk3.py", line 377, in call
    (success, pid) = self.term.spawn_sync(Vte.PtyFlags.DEFAULT,
AttributeError: 'Terminal' object has no attribute 'spawn_sync'
root@rivendell:/home/nazgul#