錯誤：在 Fedora 中使用 dnf 升級系統時 GPG 檢查失敗

今天早些時候我嘗試升級 Fedora 26 伺服器時，下載軟體包後收到以下錯誤消息：

warning: /var/cache/dnf/forensics-5e8452ee3a114fbe/packages/protobuf-c-1.3.0-1.fc26.x86_64.rpm: Header V4 RSA/SHA1 Signature, key ID 87e360b8: NOKEY
Importing GPG key 0x87E360B8:
Userid     : "CERT Forensics Operations and Investivations Team <forensics@cert.org>"
Fingerprint: 26A0 829D 5C01 FC51 C304 9037 E97F 3E0A 87E3 60B8
From       : /etc/pki/rpm-gpg/RPM-GPG-KEY-cert-forensics-2018-04-07
Is this ok [y/N]: n
Didn't install any keys
The downloaded packages were saved in cache until the next successful transaction.
You can remove cached packages by executing 'dnf clean packages'.
Error: GPG check FAILED

所以我中止了升級，我嘗試重新dnf clean packages下載，但我仍然遇到同樣的錯誤。

打包的似乎protobuf沒有有效的簽名，所以dnf不能繼續，對嗎？

但是……你說“不”：

Is this ok [y/N]: n

…當被要求安裝密鑰時！

嘗試使用 yes ( y) 代替！

使用這個命令來解決這個問題：dnf update --nogpgcheck

引用自：https://unix.stackexchange.com/questions/410049