There is not possible to get the system back working. If you haven’t done so yet, try it that way as well.The Ubuntu 20.04 hangs or freezes after some time running in VirtualBox. I’m pretty sure that the vaults as well as FF are intended to be ran on the same machine. My only helpful piece of advice is to run FF from a terminal, and see if you can catch any helpful error/debugging output. I mean, if you like node.js, have at it, but I won’t be the one that can point out what’s going wrong where.

That’s the only time that Firefox didn’t totally shit its pants when I tried to get it working.And I’m talking about the pre-compiled binary, don’t even get me started on compiling it from source. The one time I did get it to work was when I was running everything mock, and uploaded only the demo page. It was a huge PITA and I’m not quite sure that in the end I ever really solved it. HOWEVER, all that being said, I too had trouble with that pesky addon even in Debian Jessie as well as Fedora 22 & 23. I doubt anything significant has changed. The update (and links to other discussions) goes through the setup as it was then. There’s a couple things about the addon last I checked - the max amount that can be uploaded is ~1GB IIRC, and some further gotchas. That update also goes into some details about adding unsigned addons in FF43, but it doesn’t seem that you had that problem.

I’m assuming that since you pulled it from the readme.io page that it’s the one that was updated and noted in the lastest dev update.

Ubuntu virtualbox freezes