apt-get: No space left on device (12.04)

I just encountered this same problem. I elsewhere came across a mention of inodes, and ran in my terminal to check inode usage :

  df -i 

This showed inode use at 99%. So, while my disk had plenty of space left, I wasn't able to create more files because of the limit in the number of inodes. Some disk cleanup was the solution to my problem.

I'm thinking your boot partition is full of old kernel images, leaving no room for the new one apt-get is trying to install. You can type

dpkg -l linux-headers-\* linux-image-\* | grep ^ii

into a terminal window. When I do this, I get

ii  linux-headers-3.8.0-18                    3.8.0-18.28                            all          Header files related to Linux kernel version 3.8.0
ii  linux-headers-3.8.0-18-generic            3.8.0-18.28                            amd64        Linux kernel headers for version 3.8.0 on 64 bit x86 SMP
ii  linux-headers-3.8.0-19                    3.8.0-19.30                            all          Header files related to Linux kernel version 3.8.0
ii  linux-headers-3.8.0-19-generic            3.8.0-19.30                            amd64        Linux kernel headers for version 3.8.0 on 64 bit x86 SMP
ii  linux-headers-3.8.0-21                    3.8.0-21.32                            all          Header files related to Linux kernel version 3.8.0
ii  linux-headers-3.8.0-21-generic            3.8.0-21.32                            amd64        Linux kernel headers for version 3.8.0 on 64 bit x86 SMP
ii  linux-headers-3.8.0-22                    3.8.0-22.33                            all          Header files related to Linux kernel version 3.8.0
ii  linux-headers-3.8.0-22-generic            3.8.0-22.33                            amd64        Linux kernel headers for version 3.8.0 on 64 bit x86 SMP
ii  linux-headers-3.8.0-23                    3.8.0-23.34                            all          Header files related to Linux kernel version 3.8.0
ii  linux-headers-3.8.0-23-generic            3.8.0-23.34                            amd64        Linux kernel headers for version 3.8.0 on 64 bit x86 SMP
ii  linux-headers-3.8.0-25                    3.8.0-25.37                            all          Header files related to Linux kernel version 3.8.0
ii  linux-headers-3.8.0-25-generic            3.8.0-25.37                            amd64        Linux kernel headers for version 3.8.0 on 64 bit x86 SMP
ii  linux-headers-generic                     3.8.0.25.43                            amd64        Generic Linux kernel headers

Since I have quite a few, I could delete some of the oldest with

sudo apt-get remove linux-headers-3.8.0-18

If apt-get fails because it misses some package dependencies (which you can't install due to the lack of free inodes), you can resort to dpkg directly instead:

sudo dpkg --remove linux-headers-3.8.0-18

Do that a couple of times to your oldest linux-headers-* and you should have room.

I used sudo apt-get autoremove and it removed a bunch of old kernel-headers packages. Good to go after that.