Type about:crashes and copy the crash id starting with "bp-" and past it here.

whether crash happening when visiting a particular website?

Try with the beta version of firefox

• https://play.google.com/store/apps/details?id=org.mozilla.firefox_beta

I have this same problem. It just started happening. I've tried the Firefox Beta and tried reinstalling the normal Firefox, both have the same problem. They just close after a few seconds of viewing any webpage. Just do a google search and wait about 4 seconds, Firefox closes. It doesn't trigger an Android crash either. I'm really at a loss of how to investigate it. about:crashes shows nothing.