SOLVED: Problems opening tabs after upgrade from 54.0 to 55.0.2 or 55.0.3 italian version.
With version 54.0 I worked quietly with two windows, for a total of 59 tabs open.
With that version, I closed and restarted Firefox portable edition with all the tabs listed, without any problems.
But after upgrading to either italian v.55.0.2 or v.55.0.3, some cards disappear or rather reopen but no longer load contents because they have lost the URL and remain open as new tabs.
To be able to work with all 59 open tabs again, I had to make a version downgrade and restore the file sessionstore.js.
What's the problem ?