apt-get failed to upgrade

[Guest]

root@904:/home/doug# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages have been kept back:
linux-generic linux-headers-generic linux-image-generic linux-restricted-modules-generic
0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.
why is this happening

[kubicle]

Re: apt-get failed to upgrade

because 'upgrade' won't upgrade packages that due to changed dependencies would require installing new packages or remove existing packages, you need to use 'dist-upgrade' for those packages:

sudo apt-get dist-upgrade