Check your current OS version:
uname -a cat /etc/debian_version
Get up to date.
sudo apt-get update sudo apt-get upgrade sudo apt-get dist-upgrade
Verify nothing is wrong. Verify no errors are reported after each command. Fix as required (you’re on your own here!).
dpkg -C apt-mark showhold
Optionally upgrade the firmware.
Update the sources to apt-get. This replaces “stretch” with “buster” in the repository locations giving apt-get access to the new version’s binaries.
sudo sed -i 's/stretch/buster/g’ /etc/apt/sources.list sudo sed -i 's/stretch/buster/g’ /etc/apt/sources.list.d/raspi.list
Verify this caught them all. Run the following, expecting no output. If the command returns anything having previously run the sed commands above, it means more files may need tweaking. Run the sed command for each.
grep -lnr stretch /etc/apt
Speed up subsequent steps by removing the list change package.
sudo apt-get remove apt-listchanges
Do the Upgrade
sudo apt-get update && sudo apt-get upgrade -y sudo apt-get dist-upgrade -y
cleanup old outdate packages.
sudo apt-get autoremove -y && sudo apt-get autoclean
You have come this far, might as well get the latest firmware:
Have fun with your new updated Pi! 😉