I got the follow error:
W: GPG error: http://download.jitsi.org unstable/ InRelease: The following
signatures couldn't be verified because the public key is not available:
I tried to get the jitsi's key with:
wget -qO - http://download.jitsi.org/jitsi-key.gpg.key | apt-key add -
Did have some change in last days?