I am trying to install some application on Ubuntu 20.04, for that I am trying to run command on terminal
$ sudo apt update
and I have got following error
Err:1 http://dl.google.com/linux/chrome/deb stable InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 78BD65473CB3BD13
I am got the same issue while running the below command
$ sudo apt update
In your case, you can follow below option to resolved these issue.
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 78BD65473CB3BD13
Or
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 78BD65473CB3BD13
In first option, we don't have to decide which port should be or you can go with second option. Either way, both will work.