Level 66
Content Creator
Malware Hunter
Mozilla has added the ‘Clear startup cache’ button to about:support page in Firefox for users to run and fix the Startup issues browser having if any.
cleart startup cache button in about support
Sometimes, when you launch Firefox by clicking its icon on the desktop or on the taskbar, nothing happens, but you can see it running in the Task Manager and consuming memory.

When Firefox doesn’t open, it should at least show an error to understand the underlying cause to troubleshoot the issue.
Killing the Firefox process and attempts to relaunch the browser may not work all times.

In these situations, opening the Firefox browser’s startupCache folder and clearing the contents in it helps most of the time.
For this,
  • Exit Firefox by selecting the option in the menu, you can also use the shortcut Ctrl+Shift+Q for the same.
  • Run the following command in the Run dialog
  • localappdata%\Mozilla\Firefox\Profiles\
  • Open default profile
  • Open the startupCache folder, select and delete all the files in it.
Launch Firefox, it may run now without any issues

Most users not familiar with or experienced enough to follow the above steps, that’s why to fix Firefox startup issues Mozilla has added an option to about: support aka troubleshooting information page to clear startup cache in Firefox version 79.

The Troubleshooting information page already offers useful Refresh and Safe mode buttons and shows Firefox profile path and antivirus you’re running on Windows.

To Clear Firefox Startup Cache from about:support page

1. Launch Firefox

2. Visit about:support

3. Click on the button that appears below “try clearing the startup cache”

4 Firefox asks to restart and informs the user at the same time that firefox settings and extensions won’t be affected by this.

5. Click Restart.

Behind the scenes, the files in the startupCache folder will be deleted when you close Firefox and re-created upon the launch.