Upgrade from Raspbian Stretch to Raspbian Buster

busterpiupgrade.sh

#!/bin/bash

# This script is used to upgrade your Raspberry Pi OS from version 9 (stretch) to version 10 (buster).
# It is advised to keep current configuration files to avoid breaking something else and always
# take a backup image of your sd card from your Raspberry Pi prior to upgrading.
# The script must be run as root!

[ "$(whoami)" != "root" ] && echo "You must be root to run this script" && exit 1

apt update
apt dist-upgrade -y
rpi-update
grep -rl stretch /etc/apt/ | xargs sed -i 's/stretch/buster/g'

# apt-listchanges, if installed, will extend the time it takes to upgrade your system as it updates the changelog while upgrading and is not required for Raspbian to work properly
apt-get remove apt-listchanges -y
apt update
apt dist-upgrade -y
apt purge timidity lxmusic gnome-disk-utility deluge-gtk evince wicd wicd-gtk clipit usermode gucharmap gnome-system-tools pavucontrol
apt autoremove -y
apt autoclean -y
update-alternatives --set iptables /usr/sbin/iptables-legacy
update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy

# The following is for wireguard server installations only. Uncomment if needed.
# dpkg-reconfigure wireguard
# dpkg-reconfigure wireguard-tools
# dpkg-reconfigure wireguard-dkms

# Now that the installation is complete, it's time to reboot
reboot