Ошибка failed to download metadata for repo appstream

I had installed a minimalist CentOS 8 on one of my servers. Installation went successful, however, when I tried to update the system using yum update I see this error message: Failed to download metadata for repo. Below is the complete error.

[root@autocontroller ~]# 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

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]

But, then verified with the internet connection and DNS and it works just fine as below:

[root@autocontroller ~]# 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

So how did I fix the issue? Here it is.

CentOS Linux 8 had reached the End Of Life (EOL) on December 31st, 2021. It means that CentOS 8 will no longer receive development resources from the official CentOS project. After Dec 31st, 2021, if you need to update your CentOS, you need to change the mirrors to vault.centos.org where they will be archived permanently. Alternatively, you may want to upgrade to CentOS Stream.

Step 1: Go to the /etc/yum.repos.d/ directory.

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

Step 2: Run the below commands

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

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

Step 3: Now run the yum update

[root@autocontroller ~]# yum update -y

That’s it!

I’m on a fresh Centos 8 install and have tried to use yum for the first time (on this machine). I get the following for any attempt to install or update anything:

yum update
CentOS-8 - AppStream                            0.0  B/s |   0  B     00:00    
Failed to download metadata for repo 'AppStream'
Error: Failed to download metadata for repo 'AppStream'

Port 80 is open although nmap reports it as closed presumably because I haven’t yet installed apache. To be double sure I have added port 80 to firewalld which is confirmed:

firewall-cmd --list-ports
25/tcp 80/tcp

I have tried various advice like yum clean and clearing the yum cache but nothing helps.

This is what is in the dnf.log:

2020-03-30T19:33:01Z INFO --- logging initialized ---
2020-03-30T19:33:01Z DDEBUG timer: config: 4 ms
2020-03-30T19:33:01Z DEBUG Loaded plugins: builddep, changelog, config-manager, copr, debug, debuginfo-install, download, generate_completion_cache, needs-restarting, playground, repoclosure, repodiff, repograph, repomanage, reposync
2020-03-30T19:33:01Z DEBUG DNF version: 4.2.7
2020-03-30T19:33:01Z DDEBUG Command: yum install httpd 
2020-03-30T19:33:01Z DDEBUG Installroot: /
2020-03-30T19:33:01Z DDEBUG Releasever: 8
2020-03-30T19:33:01Z DEBUG cachedir: /var/cache/dnf
2020-03-30T19:33:01Z DDEBUG Base command: install
2020-03-30T19:33:01Z DDEBUG Extra commands: ['install', 'httpd']
2020-03-30T19:33:01Z DEBUG repo: downloading from remote: AppStream
2020-03-30T19:33:02Z 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).
2020-03-30T19:33:02Z DEBUG Cannot download 'http://mirrorlist.centos.org/?release=8&arch=x86_64&repo=AppStream&infra=stock': 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].
2020-03-30T19:33:02Z ERROR Failed to download metadata for repo 'AppStream'
2020-03-30T19:33:02Z DDEBUG Cleaning up.
2020-03-30T19:33:02Z SUBDEBUG 
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/dnf/repo.py", line 552, 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'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 65, in main
    return _main(base, args, cli_class, option_parser_class)
  File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 98, in _main
    return cli_run(cli, base)
  File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 114, in cli_run
    cli.run()
  File "/usr/lib/python3.6/site-packages/dnf/cli/cli.py", line 1134, in run
    self._process_demands()
  File "/usr/lib/python3.6/site-packages/dnf/cli/cli.py", line 832, in _process_demands
    load_available_repos=self.demands.available_repos)
  File "/usr/lib/python3.6/site-packages/dnf/base.py", line 406, in fill_sack
    self._add_repo_to_sack(r)
  File "/usr/lib/python3.6/site-packages/dnf/base.py", line 136, in _add_repo_to_sack
    repo.load()
  File "/usr/lib/python3.6/site-packages/dnf/repo.py", line 558, in load
    raise dnf.exceptions.RepoError(str(e))
dnf.exceptions.RepoError: Failed to download metadata for repo 'AppStream'
2020-03-30T19:33:02Z CRITICAL Error: Failed to download metadata for repo 'AppStream'