Mozilla Firefox Safe Mode Procedure:
Step 1: Click on Firefox, located at top, left side of your browser.
Step 2: Go to “Help” > “Restart with Add-ons Disabled…”.
Step 3: Mozilla Firefox asks user to Restart. “Restart” to continue to Safe Mode.
Step 4: Another pop-up asks for confirmation to enter into Safe Mode. Click “Start in Safe Mode” to continue or “Reset Firefox” to return to default (custom) version.
To check whether Mozilla Firefox has enable Safe Mode, got Firefox Add-ons Manager, press “Ctrl”+”Shift”+”A”. If you see all your add-ons (extension) disabled, it means Firefox is running in Safe Mode.
Safe Mode is a special mode where Add-ons are temporarily disabled for troubleshooting issues.