Trying to update my CentOS Linux 8 stack before upgrade to Stream

CentOS Linux 8
--------------

```sh
[root@den yum.repos.d]# cat /etc/os-release
NAME="CentOS Linux"
VERSION="8 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="8"
PLATFORM_ID="platform:el8"
PRETTY_NAME="CentOS Linux 8 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:8"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"
CENTOS_MANTISBT_PROJECT="CentOS-8"
CENTOS_MANTISBT_PROJECT_VERSION="8"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="8"

```

```sh
[root@den yum.repos.d]# uname -r
4.18.0-147.5.1.el8_1.x86_64

```

[Fix for Failed to download metadata for repo ‘AppStream’](https://techglimpse.com/failed-metadata-repo-appstream-centos-8/)
----------------------------------------------------------------------------------------------------------------------------

```
sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*

```

Errors during downloading metadata for repository 'extras'
----------------------------------------------------------

### YUM

```sh
yum clean all
yum update -y
yum check-update

```

```sh
yum update -y

```

NOTE the WARNING `Warning: failed loading '/etc/yum.repos.d/CentOS-AppStream.repo', skipping.`

```sh
Warning: failed loading '/etc/yum.repos.d/CentOS-AppStream.repo', skipping.
Repository extras is listed more than once in the configuration
CentOS-8 - Base 106 kB/s | 4.6 MB 00:44
CentOS-8 - Base 1.0 kB/s | 8.1 kB 00:08
Errors during downloading metadata for repository 'extras':
- Status code: 404 for https://vault.centos.org/centos/8/updates/x86_64/repodata/repomd.xml (IP: FILTERED)
Error: Failed to download metadata for repo 'extras': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried

```

### DNF

```sh
rm -rf /var/cache/dnf

```

```sh
dnf update --refresh

```

```sh
Warning: failed loading '/etc/yum.repos.d/CentOS-AppStream.repo', skipping.
Repository extras is listed more than once in the configuration
CentOS-8 - Base                                                                                                                               10 kB/s | 3.9 kB     00:00
CentOS-8 - Base                                                                                                                               23 kB/s | 8.1 kB     00:00
Errors during downloading metadata for repository 'extras':
  - Status code: 404 for https://vault.centos.org/centos/8/updates/x86_64/repodata/repomd.xml (IP: FILTERED)
Error: Failed to download metadata for repo 'extras': Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried

```

Any pointers on how to diagnose and resolve this issue?
=======================================================