Bookmarks.html isn't in your Profile Folder.You have to create that file yourself by pressing CTRL + SHIFT + B to open the Bookmarks Manager. At the top of the window, select Import/Backup > Export Backups by HTML

You can restore bookmarks using the existing JSON files you have by pressing CTRL + SHIFT + B again, go to Import/Backup > Restore > and either find the one you want or choose one that's located somewhere else on your computer by clicking Choose file

The .html format is ancient and Firefox doesn't create it by default.

As Moses notes, those JSON files are backups that can restore your bookmarks to the new Firefox installation. This article has more information on that: Restore bookmarks from backup or move them to another computer.

You can open about:config and put this pref in the "Search" at the top.

browser.bookmarks.autoExportHTML = double-click to toggle to true

Then close Firefox and restart it.

See also:

• http://kb.mozillazine.org/browser.bookmarks.autoExportHTML

That backup is created by default in the profile folder as bookmarks.html every time you close Firefox, but you can set the file name and path via the browser.bookmarks.file pref on the about:config page.

• http://kb.mozillazine.org/browser.bookmarks.file

The browser.bookmarks.file pref doesn't exist by default and you need to create a new String pref with the name browser.bookmarks.file and set the value to the full path of the backup bookmarks file.

Note: an HTML backup doesn't preserve tags and annotations, so you lose those if you need to import the HTML backup.

• http://kb.mozillazine.org/Export_bookmarks