you must remove both deb packages and snaps otherwise it will cause issues
before upgrade do this :
sudo apt purge firefox firefox-* sudo snap remove firefox
upgrade to 24.04 after upgrade add this mozilla respository
https://launchpad.net/~mozillateam/+archive/ubuntu/ppa
sudo apt install firefox firefox-locale-en
this should bypass snap instalation and allow you to upgrade
you must remove both deb packages and snaps otherwise it will cause issues
before upgrade do this :
sudo apt purge firefox firefox-*
sudo snap remove firefox
upgrade to 24.04
after upgrade add this mozilla respository
https:/ /launchpad. net/~mozillatea m/+archive/ ubuntu/ ppa
sudo apt install firefox firefox-locale-en
this should bypass snap instalation and allow you to upgrade