After yum is installed, the system prompts that the GPG key of the repository has been installed, but this software package is not applicable.

Problem: the following error is reported when you use Yum install FTP to install FTP in Linux.

Warning: rpmts_hdrfromfdno: Header V3 RSA/sha1 signature, key ID c105b9de: nokeyretrieving key from http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7 repository "CentOS-6-base-mirrors.aliyun.com" GPG key is installed, but not applicable to this package. Check whether the public key URL of the repository is correctly configured.

According to the error, we can see that there is a problem with the source of aliyun. Solution: 1. Delete the source of the old aliyun.

cd yum.repos.drm -rf CentOS-Base.repo

Note: I found by viewing the file that only the CentOS-Base.repo contains the http://mirrors.aliyun.com/centos/RPM-GPG-KEY-CentOS-7 2. Download the source of an aliyun CentOS-6

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo

Then the problem is solved, and then Yum install FTP is OK ~

After yum is installed, the system prompts that the GPG key of the repository has been installed, but this software package is not applicable.