Are sessions that I saved in Session Manager filed somewhere in Windows 7? Now that I’m using Quantum, they appear lost, which could be a tragedy.
i think they are stored in a folder called ‘sessions/’ in your Firefox profile folder.
but that will not rescue you - as you won’t have a way to review them in Firefox >= Quantum.
see also the notice at
https://addons.mozilla.org/de/firefox/addon/session-manager/