14.10 to 15.04: Cannot handle manual dpkg --configure prompts

The python script (and graphical interface) will hang when dpkg --configure (most likely, I was running dpkg --configure -a afterward) starts asking questions on how to proceed with changed config files. When there are a number of files that need to be updated, and the user has edited or changed some of them, even just a single one can cause the installer to completely hang. The button "Show Terminal" is or becomes unresponsive.

After doing manual dpkg --configure -a, and rerunning the upgrader, it will say

"Could not run the upgrade tool." (window title) --> "Could not run the upgrade tool. This is most likely a bug in the upgrade tool. Please report it as a bug using the command 'ubuntu-bug ubuntu-release-upgrader-core'." However, the report bug feature also fails:

Traceback (most recent call last):
  File "/usr/share/apport/apport-kde", line 530, in <module>
    sys.exit(UserInterface.run_argv())
  File "/usr/lib/python3/dist-packages/apport/ui.py", line 650, in run_argv
    return self.run_report_bug()
  File "/usr/lib/python3/dist-packages/apport/ui.py", line 488, in run_report_bug
    response = self.ui_present_report_details(allowed_to_report)
  File "/usr/share/apport/apport-kde", line 367, in ui_present_report_details
    desktop_info)
  File "/usr/share/apport/apport-kde", line 184, in __init__
    self.ui.ui_update_view(self)
  File "/usr/share/apport/apport-kde", line 358, in ui_update_view
    QTreeWidgetItem(keyitem, [line])
TypeError: index 0 has type 'bytes' but 'str' is expected

For good measure: this was an upgrade from KUBUNTU 14.10 Utopic Unicorn.

The output of apt-cache policy ubuntu-release-upgrader-core is:

ubuntu-release-upgrader-core:
  Installed: 1:15.04.13
  Candidate: 1:15.04.13
  Version table:
 *** 1:15.04.13 0
        500 http://nl.archive.ubuntu.com/ubuntu/ vivid/main amd64 Packages
        100 /var/lib/dpkg/status

But this is obviously after the upgrade. The system prior to upgrade was a regular 14.10 with a few minor tweaks.

There is another error that popped up, it may be coming from muon-upgrader or that python thing at the same time as the other error (dialog) (popup) and that is that "Verifying the upgrade failed. There may be a problem with the network or with the server."

(It appears as though after the dpkg --configure -a, my install is complete, ie. I have upgraded to Vivid. I have not rebooted yet though.)