Sometimes, you have downloaded corrupted files of Mozilla Firefox because you have opened it and with a flash for a second, it has closed instantly. Again, you tried, but it has crashed finally. To remove it, delete all cache because these are mismatching or missed one during Firefox computing. You can update the Mozilla Firefox with the latest version. Scan your pre-installed files for viruses and malware. Check if it is resolved, if no, follow the process of attaching with Mozilla Customer Care Service to troubleshoot this error finally.
Read more: - https://www.customerhelpsupport.com/how-to-fix-firefox-keeps-crashing-constantly-on-start-up/