I got issue in centos
Error: Failed to download metadata for repo ‘AppStream’: Cannot prepare internal mirrorlist |Centos

try below steps:

Please mentions your issue messages and solution too

my Solution to this issue is
Solution.1

Go to /etc/yum.repos.d/

cd /etc/yum.repos.d/

Run

sudo sed -i ‘s/mirrorlist/#mirrorlist/g’ /etc/yum.repos.d/CentOS-*
sudo sed -i ‘s|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g’ /etc/yum.repos.d/CentOS-*
sudo yum update -y

i was still getting error below

CentOS Linux 8 – AppStream 111 B/s | 38 B 00:00
Error: Failed to download metadata for repo ‘appstream’: Cannot prepare internal mirrorlist: No URLs in mirrorlist

Solution worked.

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-*