Cannot run system update

humm yes yunohost tools regen-conf can’t work for this issue since you’re not using yunohost

can you rerun this exact line, by copying it and not typing it (the line that you put in your last message is not good, because of the wrong kind of quotes":
sudo apt-key del 95BD4743; wget -nv -O - "" | sudo apt-key add -

then, to upgrade your system while not using the web interface:
sudo apt update && sudo apt upgrade