我安装了 ubuntu 24.04 但是当我使用 sudo apt update 时出现此错误:
kavus@kavus-HP:~$ sudo apt update
[sudo] password for kavus:
N: Missing Signed-By in the sources.list(5) entry for 'http://security.ubuntu.com/ubuntu'
Types: deb
URIs: https://ir.ubuntu.sindad.cloud/ubuntu/
Suites: noble noble-updates noble-backports
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
sudo cat /etc/apt/sources.list.d/ubuntu.sources
Types: deb
URIs: http://security.ubuntu.com/ubuntu/
Suites: noble-security
Components: main restricted universe multiverse
Signed-By: /usr/share/keyrings/ubuntu-archive-keyring.gpg
请帮助我,我不知道我该怎么办:(