"An error occurred while attempting to verify Thomas Voegtlin (
https://electrum.org) (7F9470E6): Invalid digest algorithm."
That's rare... the Key-ID looks fine but where did you downloaded the pubkey?
How about GPG, have you downloaded the latest version from the legit source or is it preinstalled in your system?
Try to get everything to the latest version, then retry.
For reference, here's a reliable source of their public keys:
github.com/spesmilo/electrum/tree/master/pubkeysThe problem was with my PGP keys.
They were very old, from 2013. I deleted the old ones and created two new keys, and I was able to verify Thomas Voegtlin's public key.