Hello colleagues,
I just wanna share my little story. At that time, I’ve got notification on my machine (yes Ubuntu) that there is a new kernel update. But when I select and click on Install button from update manager, the dialog box was showed with message about /boot space size issue. Ups… I couldn’t update my machine. Spending a little time to browse then found this link.
It is because I had updated my machine 5 times already, so my /boot (100MB) folder already full with a bunch of files. What I need is to clean up and erase unnecessary kernel. What I do to fix the issue are as follows :
1. I check current kernel by this line of code
uname -a; dpkg -l | grep linux-image
My current kernel
2. I need to delete unnecessary (previous) kernel on my machine. Then I created my code like below :
sudo apt-get --purge linux-image-2.6.32-24-generic linux-image-2.6.32-25-generic linux-image-2.6.32-26-generic;
sudo dpkg -P linux-image-2.6.32-21-generic;
sudo apt-get --purge autoremove;
sudo apt-get update; sudo apt-get -f install;
sudo apt-get dist-upgrade;
sudo apt-get clean
3. Well done, the latest kernel already install. Yippeee 
Reference : https://answers.launchpad.net/ubuntu/+source/update-manager/+question/93412
