Which Firefox ESR release still support XUL?
FF57 stopped supporting XUL ("legacy") add-ons.
Which latest Firefox ESR release does still support them, and when that support will cease as well?
There's no clear answer to the above on Firefox ESR pages.
Firefox 52 ESR and 52.8.0esr out in May 2018 will likely be the last update.Read this answer in context 2
Additional System Details
- Shockwave Flash 27.0 r0
- User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:56.0) Gecko/20100101 Firefox/56.0
Firefox 52 ESR and 52.8.0esr out in May 2018 will likely be the last update.