Browser crashes at startup
I bought a new system with latest OS Big Sur, I'm using Firefox v49.1 (required version) for my official purpose. So I installed this version in my Mac and it works smoothly, suddenly it quits and showing crash alert. I reinstalled again and again, but it's not worked. I fed up with this issue. Please guide me to solve this. Previously I was using Mac with High Sierra OS. That time I haven't face this issue ever.
I strongly recommend updating to the most recent version of Firefox - the copy that you are using is about five years old and has had many updates since to fix security and stability issues.