No space left on device /boot

Problem

No space left on device /boot

$ df
Filesystem                    1K-blocks      Used Available Use% Mounted on
...
/dev/sda1                        233191    216985      3765  99% /boot
...

$ sudo apt-get update
...
gzip: stdout: No space left on device
E: mkinitramfs failure cpio 141 gzip 1
...

Solution

Remove old kernel versions. See: http://askubuntu.com/questions/2793/how-do-i-remove-or-hide-old-kernel-versions-to-clean-up-the-boot-menu

After removal df shows more space:

$ df
Filesystem                    1K-blocks      Used Available Use% Mounted on
...
/dev/sda1                        233191    150530     70220  69% /boot
...
$ df -h
Filesystem                     Size  Used Avail Use% Mounted on
...
/dev/sda1                      228M  148M   69M  69% /boot
...