Rocky Linux 9 migration from Rocky Linux 8:
===========================================
# Note, this is based off the information listed here: https://computingforgeeks.com/upgrade-to-rocky-linux-9-from-rocky-linux-8/

# Note, I did this on a remote server, so for me this was not a GUI boot

# Backup your system prior to doing this!

# All commands run as root user


# Make sure at current updates and reboot if needed after updates:
dnf update -y

# Add Rocky Linux 9 Repositories
REPO_URL="https://download.rockylinux.org/pub/rocky/9/BaseOS/x86_64/os/Packages/r"
RELEASE_PKG="rocky-release-9.0-2.2.el9.noarch.rpm"
REPOS_PKG="rocky-repos-9.0-2.2.el9.noarch.rpm"
GPG_KEYS_PKG="rocky-gpg-keys-9.0-2.2.el9.noarch.rpm"
dnf -y install $REPO_URL/$RELEASE_PKG $REPO_URL/$REPOS_PKG $REPO_URL/$GPG_KEYS_PKG

# Remove old packages and files, if installed
dnf -y remove rpmconf yum-utils epel-release
rm -rf /usr/share/redhat-logos

# Install Required Rocky Linux 9 Packages
dnf -y --releasever=9 --allowerasing --setopt=deltarpm=false distro-sync

# Show current kernel versions
rpm  -qa | grep kernel | sort

# Because of the warning running rpm, rebuild the RPM repository
cd /var/lib/rpm 
rm -f __db.00*
rpm --rebuilddb

# Show current kernel versions
rpm  -qa | grep kernel | sort

# Remove the old kernel
Example:
rpm -e --nodeps  `rpm -qa|grep -i kernel|grep 4.18`

# Show old kernel is removed
rpm  -qa | grep kernel | sort

# If there is no 5.x kernel on your system, install it using the command:
# Note, this was not needed for me:
# dnf -y install kernel kernel-core shim

# List enabled modules:
dnf module list

# Disable enabled modules:
Example:
dnf module disable perl container-tools llvm-toolset virt perl-IO-Socket-SSL perl-libwww-perl python36 perl-DBI perl-DBD-SQLite
# Note, for me this was:
dnf module disable httpd perl perl-IO-Socket-SSL perl-libwww-perl satellite-5-client virt

# Update the system
# Note, for me there were no updates
dnf update -y

# Verify still in non-graphical user or server mode:
systemctl get-default
multi-user.target

# Reboot
reboot

# Check OS version
cat /etc/system-release

# Update the system
dnf update -y

# Install any preferred tools
Example:
dnf install vim