@Sylvander :-
Mm-hm. Yep; as I expected. The glibc is too old.
In recent years, I've built a version of Pale Moon to use a much newer version of glibc, that's included in the portable directory, following watchdog's lead some years ago. I was also able to use this same principle to enable glibc-tweaked older versions of Firefox.
Current, modern Firefox, however, doesn't seem "amenable" to this same trick. I tried re-building the current build of Firefox - the same one I uploaded for you to try - to use the same glibc 'tweak'.....and it point-blank refused to have anything to do with it. It wouldn't even start, and was spitting out so many errors in the terminal it actually put Chrome's output to shame!
.....and THAT takes some doing, believe me.
Don't take this the wrong way, but I would seriously recommend upgrading to a newer Puppy for online stuff. You could install a 'frugal' install of a newer Puppy alongside your existing Slacko 570......without upsetting the apple-cart in the slightest.
We've developed an entire range of 'portable' browsers, that run from outside the 'save'; this prevents the cache from bloating your 'save' with all the crap it insists on hoarding (and this stuff can build up VERY quickly). The profile & cache remain within the portable directory at all times.
(I don't mind admitting that, while up-to-date browsers were still available for it, I loved my Slacko 570. As far as I was concerned, it was the bee's knees; nothing could touch it for stability, and I swore blind I'd stick with it for ever! But gradually software stopped working with it - especially browsers - and although I'm happy to stick with a lot of older software which does what I want (if it 'works', why try to 'fix it', y'know?), browsers are the one thing I do insist on keeping 'current'. The internet is the biggest attack vector bar none; why give it the slightest excuse to dump 'nasties' on your doorstep?)
Mike.