What seems to have happened:
/ was full, then Ubuntu created a new partition, in RAM memory, to use temporarily.
Now, this 1MB partition is not big enough for the job, either.
What we can do:
1) increase the size of this partition just to do the upgrade
2) actually delete enough files in the HD that this partition is no longer needed.
To do 1:
open a terminal and run
sudo umount /tmp
sudo mount -t tmpfs -o size=1048576,mode=1777 overflow /tmp
This should give you an 1MB partition (just like the one you had =P).
Now, to increase the size, you increase the
size in that line, so that, with
size=10485760, you'd get 10 MB.
Your goal is to find a number that is enough for the job, but leaves enough ram too
To do 2:
Open a terminal and run
sudo umount /tmp or, if that fails,
sudo umount -l /tmp.
Then clean up!
Delete files in
/tmp is the thing actually in your HD, rather than a virtual ram disk), uninstall unused packages, delete files in your home folder and so on.