I have Ubuntu 20.04 computer with skype installed. When I update software using apt update, I get an error
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://repo.skype.com/deb stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 1F3045A5DF7587C3 W: Failed to fetch https://repo.skype.com/deb/dists/stable/InRelease The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 1F3045A5DF7587C3 W: Some index files failed to download. They have been ignored, or old ones used instead.
To fix this error, delete the key
sudo apt-key del 1F3045A5DF7587C3
Add the key again with
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 1F3045A5DF7587C3
Now you can update software with
sudo apt update sudo apt upgrade -y
See Skype