I have been googling for hours trying to find a way to get rid of the annoying gpg-error referring to the link below.
W: GPG error: http://download.opensuse.org Release: The following signatures could not be verified because the public key is not available: NO_PUBKEY 9A5EED8CBCA00D90
I have tried:
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 9A5EED8CBCA00D90
but to no avail.
Google Translated error message:
The following signatures could not be verified because the public key is not available