There are a number of "problem reports" in the reviews: https://addons.mozilla.org/firefox/addon/lazarus-form-recovery/reviews/ Since the author may not be updating this extension any more, if it is essential, you could consider using a different Firefox version, in particular, the "extended support release" of Firefox 52 (AKA "ESR"). That is a version of Firefox 52 which will get security patches over the next 10 months or so, but no new features. Download page: https://www.mozilla.org/firefox/organizations/all/ You'll notice at least two different downloads for Windows: <ul> <li><strong>Windows</strong> installer is the <strong>standard version for Windows</strong> that runs on both 32-bit and 64-bit Windows Vista through 10 (and 32-bit XP), the best choice for most users</li> <li><strong>Windows 64-bit</strong> installer might require some extra file cleanup but it seems you already made the switch, so this may not be necessary for you: [[How to switch from 32-bit to 64-bit Firefox]]</li> </ul>

Many thanks