That is, the Firefox browser does not start, nothing happens.
I've installed the latest version of Firefox 54 for Mac. Firefox 54 does not work on my Mac Mini desktop computer with the El Capitan OS X.
Firefox 54 does not work on my Mac Mini desktop computer with the El Capitan OS X.
Mozilla will end support for Firefox on OS X 10.6, 10.7, and 10.8 in August, 2016.
At that time, Firefox will continue to function on these platforms but will no longer receive new feature or security updates.
When I click onto the Firefox 54 icon after installation, the Firefox menu bar at the top of the computer greys out and nothing else happens. Since I installed the earlier version of Firefox it has been working for me even though it updated itself to the latest version. Read this answer in context Many have reported problems with v54.
That is, the Firefox browser does not start, nothing happens. But I'll keep these tips in mind should there be an issue in the future. For now, consider this; Install Older Version Of Firefox Be sure to read everything here.
I've installed the latest version of Firefox 54 for Mac. If you still want to downgrade, look under; I still want to downgrade.