我在AZURE上启动了一个NVIDIA虚拟机，并try 使用
Hit:2 http://azure.archive.ubuntu.com/ubuntu focal InRelease
Hit:3 http://azure.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:4 http://azure.archive.ubuntu.com/ubuntu focal-backports InRelease
Hit:5 https://packages.microsoft.com/repos/azure-cli focal InRelease
Hit:6 http://security.ubuntu.com/ubuntu focal-security InRelease
Err:1 http://developer.download.nvidia.com/compute/cuda/repos/ubuntu2004/x86_64 InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A4B469963BF863CC
Reading package lists... Done
W: GPG error: http://developer.download.nvidia.com/compute/cuda/repos/ubuntu2004/x86_64 InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A4B469963BF863CC
E: The repository 'http://developer.download.nvidia.com/compute/cuda/repos/ubuntu2004/x86_64 InRelease' is no longer signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
安装我用过的 keys
但这不会导致数据错误.gpg: keyserver receive failed: No data
我可以运行sudo apt-get upgrade次，但无法更新.
尽管安装了cuda，但它仍然找不到cuda库，这可能是由于更新.