Firefox Keeps Quitting - Apple Mac

If Firefox keeps quitting, you can try these things.

1. Restart Mac in Safe Boot Mode

2. Download Firefox again, and when it asks if you want to replace the copy you already have, say yes.

The second fix worked for me on both Macbook and Mac Mini.

What is safe mode?

Safe mode (sometimes called safe boot) is a way to start up your Mac so that it performs certain checks and prevents some software from automatically loading or opening. Starting your Mac in safe mode does the following:

• Verifies your startup disk and attempts to repair directory issues, if needed
• Loads only required kernel extensions
• Prevents startup items and login items from opening automatically
• Disables user-installed fonts 
• Deletes font caches, kernel cache, and other system cache files

If your Mac has an issue that goes away when you start up in safe mode, you might be able to isolate the cause.

Start up in safe mode

To start up in safe mode:

1. Start or restart your Mac, then immediately press and hold the Shift key. The Apple logo appears on your display. If you don't see the Apple logo, learn what to do.
2. Release the Shift key when you see the login window. If your startup disk is encrypted with FileVault, you might be asked to log in twice: once to unlock the startup disk, and again to log in to the Finder.

To leave safe mode, restart your Mac without pressing any keys during startup.

If an issue doesn't happen in safe mode

If an issue doesn't happen when your Mac is started in safe mode, try restarting without pressing any keys.

• If the issue comes back, you might have incompatible login items.
• If the issue doesn't come back, it was probably caused by a cache or directory issue with your startup disk, which safe mode fixed.