Given I have spotify installed on my ubuntu system When i upgrade using:
sudo apt-get update
Then I get this error:
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://repository.spotify.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 13B00F1FD2C19886 W: Failed to fetch http://repository.spotify.com/dists/stable/InRelease W: Some index files failed to download. They have been ignored, or old ones used instead.