There is at least one partition which ran out of space:
4.0G 4.0G 0 100% /
This is usually a bad thing. If your /var/ directory is mounted there, you are in trouble.
To see which directories take up that space, go to the root directory of that partition and say:
du -h | grep ^[0-9][0-9]*M
which give you a list with all directories or files > 10MB