ubuntu focal InRelease 没有数字签名 解决办法

E: 无法下载 http://ppa.launchpad.net/morphis/anbox-support/ubuntu/dists/focal/InRelease 403 Forbidden [IP: 185.125.190.52 80]
E: 仓库 “http://ppa.launchpad.net/morphis/anbox-support/ubuntu focal InRelease” 没有数字签名。
N: 无法安全地用该源进行更新，所以默认禁用该源。
N: 参见 apt-secure(8) 手册以了解仓库创建和用户配置方面的细节。

1. 删除冲突的源

sudo rm /etc/apt/sources.list.d/*

2.更换阿里源

sudo vi /etc/apt/sources.list

#/etc/apt/sources.list 文件里的内容换成阿里源

deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

3.更新源

sudo apt-get update