The best and most efficient way to fix the ‘XPCOM’ error is to perform a clean install of your software. You can follow the step below to do a clean reinstall of Firefox:
• Step 1: Download the latest version of Firefox and save the setup file. • Step 2: Close all Firefox windows and delete the Firefox installation folder. • Step 3: Double-click the downloaded installation file and follow the steps. • Step 4: When the installation wizard is finished you will need to directly open Firefox to check if the issue is resolved.
If you find that the ‘XPCOM’ error persists you can call the Mozilla Firefox customer service number and ask for additional technical assistance.