The SNAP version of FIREFOX installed with UBUNTU 22.04.1 --DOES NOT ACCESS-- your old profile correctly, when you upgrade from UBUNTU 20.04 (At least it did not for me.)
IT CAN NOT, because SNAP software versions are sandboxed, and the install process does not take this into proper consideration. It appears that some folks who only use LTS versions, and do not use the bleeding edge software updates on a constant basis are the ones that have had problems with the recent forced SNAP implementations.
As an FYI, your previous firefox profile is either under ~/.mozilla/firefox
or ~/.mozilla-firefox/firefox
depending on when you first installed firefox.
A second issue is that if you are using a locally designed and maintained HTML file (not directly displayed by an HTML server) as your FIREFOX home page, the snap version cannot properly access the profile or homepage unless they are actually inside the sandboxed directory.
I have not researched where the sandbox is really located, as I do not use the SNAP version of FIREFOX.
How do I know this? I have (or had) both of those problems. However, a warning: if you do as I did, and follow the instructions to install the ".deb" version of Firefox may lead into other problems such as delayed updates to FIREFOX, or constant reminders that say
Update Available.
Firefox couldn't update automatically. Download the new
version - you won't lose saved information or customizations.
However, Using the suggested download button accomplishes nothing, and I have not found a resolution to this new problem...
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@rapre I believe this is the instructions that I followed to install firefox as a ".deb" rather than as a snap.
https://www.omgubuntu.co.uk/2022/04/how-to-install-firefox-deb-apt-ubuntu-22-04
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