Thanks for your report.
The upgrader fails to calculate the upgrade because you have non-
official versions of libstdc++6 and gcc-4.9 installed on your system.
These packages cannot be upgraded and hold back several dependant
packages like libqt5core.
Here is the relevant part of the log
809 Inv
Status changed to 'Confirmed' because the bug affects multiple users.
** Changed in: ubuntu-release-upgrader (Ubuntu)
Status: New => Confirmed
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https://bugs.launchpad.net/bugs/1310
** Tags added: elementary
** Changed in: ubuntu-release-upgrader (Ubuntu)
Importance: Undecided => High
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https://bugs.launchpad.net/bugs/1310325
Title:
Upgrade from 13.10 to 14.04 f
