Comment 14 for bug 1286836

For the record:

This happened to me during a distribution upgrade from 13.10 (saucy) to 14.04 (trusty). When it happened, the release upgrade tool interrupted itself with a dialog box containing this alarming and not very helpful message:
Could not install the upgrades
The upgrade has aborted. Your system could be in an unusable state. A recovery will run now (dpkg --configure -a).

This dialog box was modal, preventing me from scrolling or copying the text in the Terminal widget to see what really happened. The text visible in the Terminal widget did not show up in any of the /var/log/dist-upgrade/* logs, but it was clearly a python exception and stack trace.

Upon closing the dialog box, the upgrade continued, contrary to what the alarming message stated. (I guess the message was referring to one particular package, not the overall release upgrade, but most end users wouldn't know that, and even if they did the message didn't state which package.)

As the upgrade continued, I was unable to copy & paste the stack trace before it was pushed out of the Terminal widget's rather short scroll buffer.