Error: Failed to download metadata for repo ‘appstream’: Cannot prepare internal mirrorlist: No URLs in mirrorlist — Centos 8 Fix
Go to the /etc/yum.repos.d/ directory.
cd /etc/yum.repos.d/
Run the below commands to hash the mirror-list in all yum.repos.d files then replace the existed Baseurl with the vault.centos.org
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-*
Then run yum update or install any package you want
yum update -y
reboot
Sending Mail error: /usr/sbin/sendmail: No such file or directory ……………… Message not sent.
sudo dnf install mailx
yum install postfix -y
service postfix start
chkconfig postfix on