Get:5 https://repo.arrayfire.com/debian all InRelease [4293 B]
Err:5 https://repo.arrayfire.com/debian all InRelease
The following signatures were invalid: EXPKEYSIG 34EF51520DCB6543 ArrayFire <technical@arrayfire.com>
Reading package lists... Done
W: GPG error: https://repo.arrayfire.com/debian all InRelease: The following signatures were invalid: EXPKEYSIG 34EF51520DCB6543 ArrayFire <technical@arrayfire.com>
E: The repository 'https://repo.arrayfire.com/debian all InRelease' is not 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.
Following the instructions here: https://github.com/arrayfire/arrayfire/wiki/Install-ArrayFire-From-Linux-Package-Managers
When trying to use the key from https://repo.arrayfire.com/GPG-PUB-KEY-ARRAYFIRE-2020.PUB the
apt-updatecommand will complain about an expired key: