Installation crashes on 75% [libsane-common]

[trintadosete]

If it had happened only once, I would call it a coincidence or result of another error (probably my fault, once I fiddle a lot with my kubuntu).

However, it happened twice in two different machines (PC, 64 bits). So, here is what happened:

I was upgrading from 15.04, but I had to leave the computers unattended. Coincidently, I got away from them while they were installing the packages (after downloading them).
When I came back, they were both locked. I unlocked the screen and the installation process was stuck on libsane-common (75% in one computer and 78% in the other). The windows was not responding to clicks. So, I rebooted both. They loaded perfectly fine (as nothing have ever happened), but I had to run dpkg --configure -a before using apt-get. One I did it, everything seems to be perfectly fine.

I cant imagine the reason why the installer would crash exactly at the same (apparently unimportant) point, but it seems to be a bug...

[Guest]

I remembered to disable my screen lock, but my install has also been stalled at "configuring libsane-common" for the last 30 minutes. Based on logs I've included below, my guess is that the install process tried to ask a question, but KDE was already in too weak of a state to be able to provide a popup.

/var/log/dist-upgrade/main.log contains the following:

2015-10-28 11:56:29,428 DEBUG got a conffile-prompt from dpkg for file: '/etc/sane.d/dll.conf'
2015-10-28 11:56:29,503 DEBUG UI version is 4.0
2015-10-28 11:56:29,503 DEBUG uiname is dialog_conffile
2015-10-28 11:56:29,503 DEBUG toplevel widget is QDialog
2015-10-28 11:56:29,503 DEBUG setting property geometry
2015-10-28 11:56:29,503 DEBUG setting property windowTitle
2015-10-28 11:56:29,503 DEBUG setting property modal
2015-10-28 11:56:29,503 DEBUG push QDialog dialog_conffile
2015-10-28 11:56:29,504 DEBUG push QGridLayout gridlayout
2015-10-28 11:56:29,504 DEBUG setting property text
2015-10-28 11:56:29,504 DEBUG push QPushButton show_difference_button
2015-10-28 11:56:29,504 DEBUG pop widget QPushButton show_difference_button
2015-10-28 11:56:29,505 DEBUG new topwidget <PyQt5.QtWidgets.QDialog object at 0x7f788f22cca8>
2015-10-28 11:56:29,505 DEBUG setting property sizePolicy
2015-10-28 11:56:29,506 DEBUG setting property text
2015-10-28 11:56:29,506 DEBUG setting property pixmap
2015-10-28 11:56:29,506 DEBUG setting property wordWrap
2015-10-28 11:56:29,507 DEBUG push QLabel textLabel2
2015-10-28 11:56:29,507 DEBUG pop widget QLabel textLabel2
2015-10-28 11:56:29,507 DEBUG new topwidget <PyQt5.QtWidgets.QDialog object at 0x7f788f22cca8>
2015-10-28 11:56:29,507 DEBUG setting property text
2015-10-28 11:56:29,507 DEBUG setting property wordWrap
2015-10-28 11:56:29,507 DEBUG push QLabel label_conffile
2015-10-28 11:56:29,507 DEBUG pop widget QLabel label_conffile
2015-10-28 11:56:29,507 DEBUG new topwidget <PyQt5.QtWidgets.QDialog object at 0x7f788f22cca8>
2015-10-28 11:56:29,507 DEBUG setting property text
2015-10-28 11:56:29,507 DEBUG push QPushButton keep_button
2015-10-28 11:56:29,507 DEBUG pop widget QPushButton keep_button
2015-10-28 11:56:29,507 DEBUG new topwidget <PyQt5.QtWidgets.QDialog object at 0x7f788f22cca8>
2015-10-28 11:56:29,507 DEBUG setting property text
2015-10-28 11:56:29,507 DEBUG push QPushButton replace_button
2015-10-28 11:56:29,507 DEBUG pop widget QPushButton replace_button
2015-10-28 11:56:29,507 DEBUG new topwidget <PyQt5.QtWidgets.QDialog object at 0x7f788f22cca8>
2015-10-28 11:56:29,508 DEBUG push QTextEdit textview_conffile
2015-10-28 11:56:29,508 DEBUG pop widget QTextEdit textview_conffile
2015-10-28 11:56:29,509 DEBUG new topwidget <PyQt5.QtWidgets.QDialog object at 0x7f788f22cca8>
2015-10-28 11:56:29,509 DEBUG pop layout QGridLayout gridlayout
2015-10-28 11:56:29,509 DEBUG pop widget QDialog dialog_conffile
2015-10-28 11:56:29,509 DEBUG new topwidget None
2015-10-28 11:56:29,588 ERROR not handled exception in KDE frontend:
Traceback (most recent call last):

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/wily", line 8, in <module>
    sys.exit(main())

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeMain.py", line 240, in main
    if app.run():

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeController.py", line 1837, in run
    return self.fullUpgrade()

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeController.py", line 1802, in fullUpgrade
    if not self.doDistUpgrade():

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeController.py", line 1143, in doDistUpgrade
    res = self.cache.commit(fprogress,iprogress)

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeCache.py", line 267, in commit
    apt.Cache.commit(self, fprogress, iprogress)

  File "/usr/lib/python3/dist-packages/apt/cache.py", line 501, in commit
    # which is less than optimal!

  File "/usr/lib/python3/dist-packages/apt/cache.py", line 465, in install_archives

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeView.py", line 234, in run
    res = os.WEXITSTATUS(self.wait_child())

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeViewKDE.py", line 451, in wait_child
    self.update_interface()

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeViewKDE.py", line 430, in update_interface
    InstallProgress.update_interface(self)

  File "/usr/lib/python3/dist-packages/apt/progress/base.py", line 252, in update_interface
    self.conffile(match.group(1), match.group(2))

  File "/tmp/ubuntu-release-upgrader-7os7i2a5/DistUpgrade/DistUpgradeViewKDE.py", line 339, in conffile
    self.confDialogue.show_difference_button.clicked.connect(self.showConffile())

TypeError: argument 1 has unexpected type 'NoneType'

From /var/log/dist-upgrade/apt-term.log, I see:

Installing new version of config file /etc/sane.d/canon_dr.conf ...

Configuration file '/etc/sane.d/dll.conf'
 ==> Modified (by you or by a script) since installation.
 ==> Package distributor has shipped an updated version.
   What would you like to do about it ?  Your options are:
    Y or I  : install the package maintainer's version
    N or O  : keep your currently-installed version
      D     : show the differences between the versions
      Z     : start a shell to examine the situation
 The default action is to keep your current version.
*** dll.conf (Y/I/N/O/D/Z) [default=N] ?

[vinnywright]

this dose seam to be a bug of sorts ,,,,,,,I have seen a few similar posts .

it seams that if you are doing the release-upgrade in a GUI you will not see/get a pop-up for the question and so can not answer it .
this is not the first time I have read of such a thing and not just recently ,,,,,,,one more reason I do such things in the CLI ,,,,,,,

sudo do-release-upgrade

VINNY

[trintadosete]

Pretty lame error...

It happened to me again (I upgraded before reading the answers here).

Thank you for the answers!