Export them as HTML the notes are still there for now. :

• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

Can drag and drop into any open browser window to view.

This can but is from scratch. https://testpilot.firefox.com/experiments/notes/

Please see this : https://support.mozilla.org/en-US/questions/1232448

Pkshadow said

Export them

I don't want to export them. I just want to USE them, descriptions are really important to me for collecting data (saving summaries) of what I've read/watched.

Zotero kills folder hierarchy, btw.

Do what you would like, I have provided information.

Here is the info from Help --> About --> What's New ver 62 Removed the description field for bookmarks. Users who have stored descriptions using the field may wish to export these descriptions as html or json files, as they will be removed in a future release.

If you do not export a copy to HTML you will loose your notes.

Besides, that is how you back them up and should be doing always as it is a computer program. Rule of thumb/ Rule of chance, Regret the day you do not do it.