Unable to install updates - spotify repository key

[stevef]

Looks like the spotify security key needs updating (or adding).

Open a terminal by pressing Ctrl Alt and T together.
Enter this command to get the new spotify key and install it.

Code:

sudo curl -sS https://download.spotify.com/debian/pubkey_C85668DF69375001.gpg | sudo gpg --dearmor --yes -o /etc/apt/trusted.gpg.d/spotify.gpg

You may need to enter your password.
Follow any on-screen instructions to confirm the action.

Then try running the update/upgrade again.