The title pretty much says it all. I am using Ubuntu Mate, so Firefox is available from the main repository.
Firefox has not worked on the Raspberry Pi since Firefox 55. I hoped that Firefox 56 would fix the issue, but it did not. Now apparently the latest Firefox (57) has been rebuilt to some degree, and although the chances of the bug being fixed is slight, there is always hope.
Has anyone tried it yet? If so, please post your results. If nobody posts, I will be the guinea pig.