Showing Error: Failed to Download Metadata for Repo ‘AppStream’- CentOS

This post will explain how to resolve the CentOS 8 error “Failed to download metadata for repo AppStream.”
On one of the servers, for instance, you have installed a basic version of CentOS 8. The installation process is successful and runs smoothly throughout.

But, while updating the system, using the yum update, you’re likely to get the error message, “Failed to download metadata for repo”

Here is the error you’ll get:

[root@server ~]# yum update
CentOS-8 - AppStream 70 B/s | 38 B 00:00
Error: Failed to download metadata for repo 'AppStream': Cannot prepare internal mirrorlist: No URLs in mirrorlist

Now the output from the /var/log/dnf.log for more debug information:

2022-02-02T11:39:36Z DEBUG error: Curl error (6): Couldn't resolve host name for http://mirrorlist.centos.org/?release=8&arch=x86_64&repo=AppStream&infra=stock [Could not resolve host: mirrorlist.centos.org] (http://mirrorlist.centos.org/?release=8&arch=x86_64&repo=AppStream&infra=stock).
2022-02-02T11:39:36Z WARNING Errors during downloading metadata for repository 'AppStream':
- Curl error (6): Couldn't resolve host name for http://mirrorlist.centos.org/?release=8&arch=x86_64&repo=AppStream&infra=stock [Could not resolve host: mirrorlist.centos.org]
2022-02-02T11:39:36Z DDEBUG Cleaning up.
2022-02-02T11:39:36Z SUBDEBUG
Traceback (most recent call last):
File "/usr/lib/python3.6/site-packages/dnf/repo.py", line 573, in load
ret = self._repo.load()
File "/usr/lib64/python3.6/site-packages/libdnf/repo.py", line 394, in load
return _repo.Repo_load(self)
RuntimeError: Failed to download metadata for repo 'AppStream': Cannot prepare internal mirrorlist: Curl error (6): Couldn't resolve host name for http://mirrorlist.centos.org/?release=8&arch=x86_64&repo=AppStream&infra=stock [Could not resolve host: mirrorlist.centos.org]

If you verify the internet connection and DNS, it works alright as given below:

[root@server ~]# ping google.com
PING google.com (172.217.166.206) 56(84) bytes of data.
64 bytes from del03s13-in-f14.1e100.net (172.217.166.206): icmp_seq=1 ttl=115 ti me=43.5 ms
--- google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 43.508/43.508/43.508/0.000 ms

Now, how to fix this issue? Let’s see in the below steps:

FIXING THE ERROR: FAILED TO DOWNLOAD METADATA FOR REPO

CentOS Linux 9 achieved its End of Life (EOL) on December 31, 2021. This implies that it won’t get any updates on its development from the official CentOS project. After that, on December 31, 2021, you will need to switch the mirrors to vault.centos.org in order to update your CentOS. They will be permanently archived here. It could be necessary for you to switch to CentOS stream instead.

Here are the steps: Step 1:

First go to the /etc/yum.repos.d/ directory.

[root@server ~]# cd /etc/yum.repos.d/

Step2: Now, run the commands given below:

[root@server ~]# sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*

[root@server ~]# sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*

Step 3: After this, run the yum update:

[root@server ~]# yum update -y

And that’s all!

By following the above steps, you can easily fix the error, “Failed to Download Metadata for Repo ‘AppStream’.