How can I boot with an older kernel version?
The simplest way to display your Grub is to press and hold the SHIFT button while booting.
As an alternative, you can always display Grub without it booting any particular kernel:
gksudo gedit /etc/default/grub
change GRUB_TIMEOUT to -1 and comment out GRUB_HIDDEN_TIMEOUT
finish off by running
sudo update-grub
Holding down the shift key while booting, will display the Grub menu. You can now select an older kernel version.
For selecting an older kernel as the default kernel, please see this post
If you have a few Kernels in your system you can set manually what Kernel version will start:
Reboot your PC with pressed Shift button for display GRUB after BIOS will start. You will see something like:
Select "Advanced options for Ubuntu" and memorize index of this menu line(count starts from 0) On the picture index is 1
Select concrete kernel for boot and also memorize index of this menu line(count starts from 0) On the picture index of chosen Kernel is 2
Start system. This action is for one boot on concrete kernel. If you want to start from concrete Kernel all time you should do next steps:
4.1. Open and edit GRUB setup file:
sudo nano /etc/default/grub
4.2. Find line GRUB_DEFAULT=...(by default GRUB_DEFAULT=0) and sets in quotes menu path to concrete Kernel(Remember menu indexes from steps 2 and 3). In my system first index was 1 and second was 2. I set in to GRUB_DEFAULT
GRUB_DEFAULT="1>2"
Save file.
4.3. Update GRUB information for apply changes:
sudo update-grub
4.4. After reboot you automatically boot on Kernel by chosen menu path. An example on my machine 1 -> 2
4.5. Check Kernel version after reboot:
uname -r