How to Upgrade from CentOS 7 to CentOS 8

This tutorial describe how to upgrade from CentOS 7.9 to CentOS 8.2.

Things to be consider while performing the upgrade from CentOS 7.9 to CentOS8.2 👇👇👇

– Always do full backup your system before upgrade
– Actual scenario might have different situation
– Make sure, all the configured repositories should be updated and able to update package for CentOS 8

– This is an unofficial, unsupported procedure !

Here are the commands for upgrade from CentOS 7.9 to CentOS 8.2 👇👇👇
# Install the EPEL Repository, if it is not configured
yum install epel-release -y

# Install yum-utils Tools
yum install yum-utils -y

# Resolves RPM packages
yum install rpmconf -y
rpmconf -a

# Perform a clean-up of all the packages which don’t require
package-cleanup –leaves; package-cleanup –orphans

# Install dnf package in CentOS7
yum install dnf -y

# Remove yum package manager
dnf -y remove yum yum-metadata-parser
rm -Rf /etc/yum

# Upgrading CentOS7 using dnf
dnf upgrade -y

# Install CentOS 8 Release package (centos-linux-repos, centos-linux-release, centos-gpg-keys)

dnf install -y https://vault.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-linux-repos-8-2.el8.noarch.rpm https://vault.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-linux-release-8.3-1.2011.el8.noarch.rpm https://vault.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-gpg-keys-8-2.el8.noarch.rpm

# Adjusting CentOS-Linux-BaseOS Repo to avoid any error
mv /etc/yum.repos.d/CentOS-Linux-BaseOS.repo /etc/yum.repos.d/CentOS-Linux-BaseOS.repo.original

vi /etc/yum.repos.d/CentOS-Linux-BaseOS.repo
[baseos]
name=CentOS Linux $releasever – BaseOS
baseurl=https://vault.centos.org/8.2.2004/BaseOS/x86_64/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

# Upgrade EPEL and Remi Repository
dnf -y upgrade https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm https://rpms.remirepo.net/enterprise/remi-release-8.rpm

# Removing all temporary package files
dnf clean all

# Removing old Kernel code of CentOS 7
rpm -e `rpm -q kernel`; rpm -e –nodeps sysvinit-tools

# CentOS8 system upgrade
dnf -y –releasever=8 –allowerasing –setopt=deltarpm=false distro-sync

# Install new Kernel Core for CentOS 8
dnf -y install kernel-core kernel

# Install CentOS 8 Minimum Package
dnf -y groupupdate “Core” “Minimal Install”

# Optionally, install Server with GUI with following command
# dnf -y groupupdate “Server with GUI” “Server”

# Install grub2, if does not installed
dnf install grub2 -y

# Install GRUB into MBR
lsblk

# Install GRUB in the device displayed from above command.
grub2-install /dev/sda

# Make GRUB Configuration file
grub2-mkconfig -o /boot/grub/grub.cfg

# reboot the system to start the system into CentOS 8
reboot

# View the current version
cat /etc/centos-release