How to Upgrade CentOS 7 to CentOS 8

James KiarieJune 29, 2020November 11, 2019 CentOS 113 Comments

In this article, you will learn how to upgrade CentOS 7 to CentOS 8. The steps described herein do not depict the official upgrade and this should not be applied to a production server yet.

Step 1: Install the EPEL Repository

To start off, install the EPL repository by running:

# yum install epel-release -y

Step 2: Install yum-utils Tools

After successfully installing EPEL, install yum-utils by running the command below.

# yum install yum-utils

Thereafter, you need to resolves RPM packages by executing the command.

# yum install rpmconf
# rpmconf -a

Next, perform a clean-up of all the packages you don’t require.

# package-cleanup --leaves
# package-cleanup --orphans

Step 3: Install the dnf in CentOS 7

Now install dnf package manager which is the default package manager for CentOS 8.

# yum install dnf

You also need to remove the yum package manager using the command.

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

Step 4: Upgrading CentOS 7 to CentOS 8

We are now ready to upgrade CentOS 7 to CentOS 8, but before we do so, upgrade the system using the newly install dnf package manager.

# dnf upgrade

Next, install CentOS 8 release package using dnf as shown below. This will take a while.

# dnf install http://mirror.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-repos-8.2-2.2004.0.1.el8.x86_64.rpm http://mirror.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-release-8.2-2.2004.0.1.el8.x86_64.rpm http://mirror.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-gpg-keys-8.2-2.2004.0.1.el8.noarch.rpm

Next, upgrade the EPEL repository.

dnf -y upgrade https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

After successfully upgrading the EPEL repository, remove all the temporary files.

# dnf clean all

Remove the old kernel core for CentOS 7.

# rpm -e `rpm -q kernel`

Next, be sure to remove conflicting packages.

# rpm -e --nodeps sysvinit-tools

Thereafter, launch the CentOS 8 system upgrade as shown.

# dnf -y --releasever=8 --allowerasing --setopt=deltarpm=false distro-sync

Step 5: Install the New Kernel Core for CentOS 8

To install a new kernel for CentOS 8, run the command.

# dnf -y install kernel-core

Finally, install CentOS 8 minimal package.

# dnf -y groupupdate "Core" "Minimal Install"

Now you can check the version of CentOS installed by running.

# cat /etc/redhat-release

Conclusion

This article concludes on how you can upgrade from CentOS 7 to CentOS 8. We hope you found this insightful.

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113 thoughts on “How to Upgrade CentOS 7 to CentOS 8”

PB

August 18, 2020 at 7:31 am
When trying to group update about “Core” “Minimal Install“, centos system has error in yum.

Can I get the solution?

Environment
– CentOS 7.5

** Error Messages
```
# dnf groupupdate "Core" "Minimal Install"
...
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
  Preparing        :     
  Installing       : yum-4.2.17-7.el8_2.noarch     
Error unpacking rpm package yum-4.2.17-7.el8_2.noarch
  Verifying        : yum-4.2.17-7.el8_2.noarch  

Failed:
  yum-4.2.17-7.el8_2.noarch

Error: Transaction failed
```
Reply
- Milan Keršláger
  
  August 18, 2020 at 3:36 pm
  Try to use another way (as of https://serverfault.com/questions/985478/how-do-i-update-a-system-from-centos-7-to-centos-8):
```
# dnf -y --releasever=8 --allowerasing --setopt=deltarpm=false distro-sync
```
  Reply
- Grzegorz
  
  September 15, 2020 at 4:52 pm
```
# rm -Rf /etc/yum
# dnf groupupdate "Core" "Minimal Install"
```
  Reply

# dnf -y --releasever=8 --setopt=deltarpm=false --allowerasing --best distro-sync
Repository extras is listed more than once in the configuration
Repository centosplus is listed more than once in the configuration
CentOS-8 - Updates Sources          
CentOS-8 - cr                        
CentOS-8 - Base Sources              
CentOS-8 - Base   
Failed to synchronize cache for repo 'updates-source', ignoring this repo.
Failed to synchronize cache for repo 'cr', ignoring this repo.
Failed to synchronize cache for repo 'base-source', ignoring this repo.
Failed to synchronize cache for repo 'base', ignoring this repo.
Failed to synchronize cache for repo 'updates', ignoring this repo.
Last metadata expiration check: 0:09:25 ago on Sun 16 Aug 2020 10:30:35 AM CDT.
Error: 
 Problem: The operation would result in removing the following protected packages: dnf

Luxmi narasimman

September 2, 2020 at 1:42 pm

Is it solved? I m also getting the same error.
Reply

DigitalHermit

July 28, 2020 at 4:32 am

These docs should be removed as they DO NOT and WILL NOT work. Even on a clean Centos 7 system, this process will fail because of dependencies.

This procedure will break your system. It will at best, leave you spinning on the dependency check that will never complete (8+ hours and it didn’t complete), or leave you with a difficult to resolve circular dependency with python or GCC.

There are ways to unbrick a system by manually downloading and manually extracting packages to jumpstart a DNF reinstallation of broken packages, but it’s not worth it.
Reply
- Tom
  
  July 30, 2020 at 12:42 pm
  
  This doc worked for me as a charm. Thank you so much.
  Reply
  - James Kiarie
    
    July 30, 2020 at 4:40 pm
    
    I’m glad the guide was of much assistance.
    Reply
Trevor

July 21, 2020 at 1:15 am

Hi James,

Thank you for the thoughtful article.

After following this closely, I was was able to upgrade with no issue — just an old python 3.6 repo that I removed, based on the conflict report.

Very much enjoying the new Web Cockpit.

Thanks again!

Trevor
Reply
- James Kiarie
  
  July 21, 2020 at 4:16 pm
  
  Thanks Trevor, you are welcome.
  Reply
Renato

July 21, 2020 at 12:56 am
I’ve got the following error on distro-sync step:
```
Error: transaction check vs depsolve:
(gcc >= 8 with gcc < 9) is needed by annobin-8.90-1.el8.0.1.x86_64
rpmlib(RichDependencies) <= 4.12.0-1 is needed by annobin-8.90-1.el8.0.1.x86_64
(annobin if gcc) is needed by redhat-rpm-config-122-1.el8.noarch
rpmlib(RichDependencies) <= 4.12.0-1 is needed by redhat-rpm-config-122-1.el8.noarch
To diagnose the problem, try running: 'rpm -Va --nofiles --nodigest'.
You probably have corrupted RPMDB, running 'rpm --rebuilddb' might fix the issue.
The downloaded packages were saved in cache until the next successful transaction.
You can remove cached packages by executing 'dnf clean packages'.
```
Case anyone has ideas about how to fix it
Reply
- Renato
  
  July 22, 2020 at 4:59 pm
  
  Adding --best parameter to distro-sync command made it work.
  Reply
- Simone
  
  July 22, 2020 at 8:34 pm
  I’ve had the same problem and resolved it with:
```
# dnf remove perl
# dnf remove python3
```
  then
```
# dnf -y --releasever=8 --allowerasing --setopt=deltarpm=false distro-sync
```
  and reinstall perl (if necessary)
  Reply
none

July 1, 2020 at 12:24 am

This break up my distro thanks a bunch…
Reply
- Martes W.
  
  July 13, 2020 at 4:53 am
  
  Dude, these “howtos” arrive every time there is a major version update and they NEVER work for real installations.
  
  1) No Centos system I have ever run will let you remove any kernel, because, “IT IS THE KERNEL” and it refuses to do so using yum, or dnf.
  
  2) Even when you skip all of that, and just jump to the upgrade of installed packages, you end up needing to actually remove everything on the system, and then basically start from a vanilla install, and that probably still won’t work.
  
  I ALWAYS end up just fully reinstalling using media, after backing up or migrating the necessary bits from the current install.
  
  These tutorials are always worthless in the real world.
  
  I believe these guys are working with a fedora or bleeding-edge centos development branch with certain features turned off, which are never disclosed.
  Reply
  - Martes W.
    
    July 13, 2020 at 2:16 pm
    
    Also, one of the “updated” comments from a reader back in the spring indicated that they had some issues with python36-* and just “removed it” to continue. Well, I just figured I would remove the python packages that were also proving to be troublesome since this was just a development hypervisor for my openshift cluster and some other stuff. (I.E. all the important stuff is on the hardware raid built into the chassis, and I use installation ssds to run the actual OS.)
    
    So I just wanted to see how far I would get, and maybe for possibly the third major release in a row won’t force full vanilla install at some point.
    
    Welp, sure enough, once I started removing python3 stuff that it was complaining about, dnf (python app) started giving errors about not being able to find named module, etc….
    
    However, if you remember from earlier steps, you have already fully removed “yum” in place of “dnf.”
    
    However, I have also come across this exact situation when migrating from CentOS 6 to CentOS 7 before they came up with the nifty “in place update” tooling that made it so easy and less problematic.
    
    So yup, these articles are always a trip, because they never really work.
    
    I have to assume that just like the Linux “gurus” of old, where the world “worked on their box” but when you tried to find out how to build the world on yours, you were always left floating in space as they confidently indicated that “it works on their box….”
    
    I think these articles are based on a minimum-proof-of-concept that no one is actually running. (Like making some minimalist install that would require so much removal of items and packages to get back to, that you may as well just install fully with new media.)
    Reply
  - sriram
    
    July 22, 2020 at 3:01 pm
    
    “1) No Centos system I have ever run will let you remove any kernel, because, “IT IS THE KERNEL” and it refuses to do so using yum, or dnf.”
    
    Well, use rpm and put --nodeps and you can remove the kernel. But yes, if something goes wrong, you will end up bricking the system, there will be no kernel to boot into. I was able to upgrade to 8.2, had to rpm -e --nodeps the kernel; also had to remove devel packages – what I did was list the devel packages that were being removed into a file and reinstall all of them after the base upgrade was finished; had to do this for about 25 packages. Also, the upgrade usually works only at minimal install level, had to then group install development tools, systems tools, security tools, etc etc. A real pain, but possible.
    Reply
    - Martes W.
      
      July 23, 2020 at 7:06 pm
      
      Thanks for the update, but I have been holding off getting back onto that test hypervisor because I have to basically re-install python because now dnf doesn’t know how to run using python 2 or whatever is currently installed.
      
      There is always some “bricking” command included in these tutorials. I was just wondering if that were still the case, and sure enough, once I got over the hurdles referenced by the other guys, I ended up with a system that can’t install anything else, because I have uninstalled python3 and yum is gone so nothing cares about python2 or whatever is currently installed. LOL…
      Reply

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