I was trying to remove, then reinstall, tor browser. apt is now no longer working;
sudo apt update
E: Conflicting values set for option Signed-By regarding source https://deb.torproject.org/torproject.org/ focal: /usr/share/keyrings/deb.torproject.org-keyring.gpg != /usr/share/keyrings/tor-archive-keyring.gpg E: The list of sources could not be read.
I tried removing /usr/share/keyrings/deb.torproject.org-keyring.gpg and /usr/share/keyrings/tor-archive-keyring.gpg to no effect..
--reinstallparameter) should be trivial.