How to Upgrade CentOS 7 to CentOS 8 Linux

James KiarieFebruary 7, 2022November 18, 2021 CentOS 229 Comments

In this article, you will learn how to upgrade CentOS 7 to CentOS 8.5 release. 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 resolve 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 the 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://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/{centos-linux-repos-8-3.el8.noarch.rpm,centos-linux-release-8.5-1.2111.el8.noarch.rpm,centos-gpg-keys-8-3.el8.noarch.rpm}

Note: CentOS 8 is dead and all the repos have been moved to vault.centos.org.

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

Note: If you get errors about conflicting packages, for example in my case there were conflicts about the existing python36-rpmconf package. I removed this package, similarly if you get any conflicts just remove those packages and try running the above upgrade command.

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

If you see the above output, I have successfully upgraded from CentOS 7 to CentOS 8.5 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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229 thoughts on “How to Upgrade CentOS 7 to CentOS 8 Linux”

Sunil

February 2, 2023 at 10:18 pm

Hi Ravi, I am having issues when I try to – Next, install CentOS 8 release package using dnf as shown below. This will take a while.

# dnf install http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/{centos-linux-repos-8-3.el8.noarch.rpm,centos-linux-release-8.5-1.2111.el8.noarch.rpm,centos-gpg-keys-8-3.el8.noarch.rpm} CentOS-7 - Base 0.0 B/s | 0 B 00:00 CentOS-7 - Updates 0.0 B/s | 0 B 00:00 CentOS-7 - Extras 0.0 B/s | 0 B 00:00 Failed to synchronize cache for repo 'base', ignoring this repo. Failed to synchronize cache for repo 'updates', ignoring this repo. Failed to synchronize cache for repo 'extras', ignoring this repo. Last metadata expiration check: 0:01:24 ago on Thu 02 Feb 2023 04:42:15 PM UTC. [MIRROR] centos-linux-repos-8-3.el8.noarch.rpm: Curl error (56): Failure when receiving data from the peer for http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-linux-repos-8-3.el8.noarch.rpm [Recv failure: Connection reset by peer] [FAILED] centos-linux-repos-8-3.el8.noarch.rpm: Curl error (56): Failure when receiving data from the peer for http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-linux-repos-8-3.el8.noarch.rpm [Recv failure: Connection reset by peer] Curl error (56): Failure when receiving data from the peer for http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-linux-repos-8-3.el8.noarch.rpm [Recv failure: Connection reset by peer]
Any suggestions/thoughts?

Thanks
Sunil
Reply
- Ravi Saive
  
  February 3, 2023 at 11:46 am
  
  @Sunil,
  
  Check your system timezone, date, and time, and set the time and date to the current date…
  Reply
  - Sunil
    
    February 6, 2023 at 10:30 pm
    Thanks, Ravi!
    
    Changed the time and time zone. Now I am unable to remove the old kernel and also unable to upgrade the kernel version.
    
    $ rpm -e `rpm -q kernel` error: Failed dependencies: kernel >= 2.6.32 is needed by (installed) lldpad-1.0.1-7.git036e314.el7_9.x86_64 kernel >= 2.6.32 is needed by (installed) lldpad-1.0.1-7.git036e314.el7_9.x86_64
    
    [root]# dnf -y install kernel-core CentOS-7 - Base CentOS-7 - Updates CentOS-7 - Extras Failed to synchronize cache for repo 'base', ignoring this repo. Failed to synchronize cache for repo 'updates', ignoring this repo. Failed to synchronize cache for repo 'extras', ignoring this repo. Last metadata expiration check: 0:01:55 ago on Mon 06 Feb 2023 11:54:47 AM EST. No match for argument: kernel-core Error: Unable to find a match: kernel-core
    
    Any help here
    Thanks
    Sunil
    Reply
    - Ravi Saive
      
      February 7, 2023 at 12:47 pm
      
      @Sunil,
      
      There could be three reasons for getting a such error:
      
      1. Incorrect date and time settings
      2. Old dnf cache expired
      3. CentOS baseURL
      
      Fix these issues by:
      
      # timedatectl set-timezone "Asia/Kolkata" # dnf install http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/{centos-linux-repos-8-3.el8.noarch.rpm,centos-linux-release-8.5-1.2111.el8.noarch.rpm,centos-gpg-keys-8-3.el8.noarch.rpm} # dnf -y upgrade https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm # dnf clean all # rpm -e `rpm -q kernel`
      Reply
      - Sunil
        
        February 7, 2023 at 8:39 pm
        
        Hi Ravi, The server is in USA EST, so I set it to EST time.
        
        Still getting the same error –
        
        [[email protected]~]# date Tue Feb 7 10:06:07 EST 2023
        
        [[email protected]~]# dnf install http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/{centos-linux-repos-8-3.el8.noarch.rpm,centos-linux-release-8.5-1.2111.el8.noarch.rpm,centos-gpg-keys-8-3.el8.noarch.rpm} CentOS-7 - Base 0.0 B/s | 0 B 00:00 CentOS-7 - Updates 0.0 B/s | 0 B 00:00 CentOS-7 - Extras 0.0 B/s | 0 B 00:00 Failed to synchronize cache for repo 'base', ignoring this repo. Failed to synchronize cache for repo 'updates', ignoring this repo. Failed to synchronize cache for repo 'extras', ignoring this repo. Last metadata expiration check: 22:11:40 ago on Mon 06 Feb 2023 11:54:47 AM EST. [MIRROR] centos-linux-repos-8-3.el8.noarch.rpm: Curl error (56): Failure when receiving data from the peer for http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-linux-repos-8-3.el8.noarch.rpm [Recv failure: Connection reset by peer] [FAILED] centos-linux-repos-8-3.el8.noarch.rpm: Curl error (56): Failure when receiving data from the peer for http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-linux-repos-8-3.el8.noarch.rpm [Recv failure: Connection reset by peer] Curl error (56): Failure when receiving data from the peer for http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/centos-linux-repos-8-3.el8.noarch.rpm [Recv failure: Connection reset by peer]
      - Ravi Saive
        
        February 8, 2023 at 11:26 am
        
        @Sunil,
        
        It seems your curl doesn’t support SSL/TLS properly. Try to update or upgrade your system with:
        
        $ dnf update $ dnf upgrade
      - Sunil
        
        February 8, 2023 at 6:48 pm
        
        Hi Ravi, Still no luck
        
        [[email protected] ~]# dnf update CentOS-7 - Base 0.0 B/s | 0 B 00:00 CentOS-7 - Updates 0.0 B/s | 0 B 00:00 CentOS-7 - Extras 0.0 B/s | 0 B 00:00 Failed to synchronize cache for repo 'base', ignoring this repo. Failed to synchronize cache for repo 'updates', ignoring this repo. Failed to synchronize cache for repo 'extras', ignoring this repo. Last metadata expiration check: 16:13:48 ago on Tue 07 Feb 2023 04:02:13 PM EST. Dependencies resolved. Nothing to do. Complete!
        
        [[email protected] ~]# dnf upgrade CentOS-7 - Base 0.0 B/s | 0 B 00:00 CentOS-7 - Updates 0.0 B/s | 0 B 00:00 CentOS-7 - Extras 0.0 B/s | 0 B 00:00 Failed to synchronize cache for repo 'base', ignoring this repo. Failed to synchronize cache for repo 'updates', ignoring this repo. Failed to synchronize cache for repo 'extras', ignoring this repo. Last metadata expiration check: 16:14:10 ago on Tue 07 Feb 2023 04:02:13 PM EST. Dependencies resolved. Nothing to do.
        
        Complete!
        [[email protected] ~]#
      - Ravi Saive
        
        February 10, 2023 at 12:23 pm
        
        @Sunil,
        
        It looks like your repos are empty, I suggest you check the repos in /etc/yum.repos.d/ directory and see the sizes of the base, updates, and extras repository. Also, I suggest your to try to follow the instructions again from the beginning…
Donavan

January 29, 2023 at 5:09 am

Humm…

Be careful, some basic packages will be deleted with those steps of SSH service…

Regards
Reply
dargaud

January 15, 2023 at 7:19 pm
Hello,

Thanks for the instructions. It did seem easy enough to follow and worked well until:
```
# dnf --releasever=8 --allowerasing --setopt=deltarpm=false distro-sync
CentOS Linux 8 - BaseOS                                                                                      
CentOS Linux 8 - AppStream    
Failed to synchronize cache for repo 'baseos', ignoring this repo.
Failed to synchronize cache for repo 'appstream', ignoring this repo.
Last metadata expiration check: 0:01:07 ago on 2023-01-15T13:39:04 UTC.
Error: 
 Problem: The operation would result in removing the following protected packages: dnf
```
Google then took me to either irrelevant or highly complex and problematic pages… I’m going to revert my snapshot for maybe another try later.
Reply
- jd
  
  March 9, 2023 at 7:43 pm
  
  Uninstall dnf from the centos7 install before starting. Centos7 dnf uses python2, when following the process above the installation of dnf in order should pull a python3 version for you.
  Reply
Cyrus

January 4, 2023 at 3:15 pm
Hi,

I followed the procedure but at this stage:
```
# dnf -y install kernel-core
```
I’m getting the error:
```
No match for argument: kernel-core
Error: Unable to find a match: kernel-core.
```
My kernel version after running command uname -r:
```
3.10.0-957.el7.x86_64
```
Any idea appreciated.
Reply
- Ravi Saive
  
  January 5, 2023 at 10:25 am
  
  @Cyrus,
  
  To fix this problem you need to boot into rescue mode, then remove the existing linux-firmware package and then manually download and install kernel, kernel-core, and kernel-modules, linux-firmware using rpm -ivh kernel* command.
  
  After that reboot the machine…
  Reply
John

January 2, 2023 at 10:21 am
@Ravi Saive,

Works with that long sequence. I am somehow able to rpm -ivh kernel-modules after removing a lot of packages related to python3 maybe. Able to show and boot into Centos 8. But since I was deep with a lot of packages in CentOs 7, after doing a lot of dnf removal.

I ended up missing some crucial utilities after booting into CentOS 8. Ended up just reinstalling a CentOS 8. Was never able to run:
```
# dnf -y --releasever=8 --allowerasing --setopt=deltarpm=false distro-sync
```
Reply
- Ravi Saive
  
  January 2, 2023 at 12:59 pm
  
  @John,
  
  Sorry for the trouble, but I think you can install those missing utilities with dnf tool after booting into CentOS 8…
  Reply