Comment 1 for bug 1464101

That report does not provide the required info usually found (and mandatory) when reporting with 'ubuntu-bug <package>'
So its declared 'invalid'; if the problem persist, then follow the comment above.

The system needs some manual commands to be executed:
sudo apt-get clean
sudo apt-get autoclean
sudo apt-get autoremove

note: this problem is often met on systems where many old kernels upgrades are still installed, and no more needed; sadly the system does not clean itself yet (ubuntu-release-upgrader is missing such a feature to purge all the old kernels but the two last ones)