Review for Mozilla Archive Format, with MHT and Faithful Save by U.C.
Rated 5 out of 5 stars
SOLUTION FOR FIREFOX 57+
Install a second version of Firefox (v.56) and deactivate the update.
Here you can find all versions:
https://ftp.mozilla.org/pub/firefox/releases/
To create your own collections, you must have a Mozilla Add-ons account.