Note that Mozilla is changing to their "Electrolysis" addon architecture (AKA e10s), so many addons won't be compatible with FF48.
https://blog.mozilla.org/addons/2016...-electrolysis/

You can check if your addons are compatible here:
https://www.arewee10syet.com/

If you are using a lot of old addons, I recommend you switch to the ESR channel for now.