When you try to start Firefox from its shortcut on the desktop or on the Start Menu you can get Firefox.exe – System Error dialog with the message ‘The program can’t start because pgort100.DLL is missing from your computer. Try reinstalling the program to fix the problem’ followed by another error dialog ‘Couldn’t load XPCOM.’. Let us see how to fix these errors and start Firefox again.

Firefox.exe System Error pgort100.DLL missingFirefox Couldn't load XPCOM

We’ve faced similar type of error for Chrome in the past which showed “The Program can’t start because asan_rtl.dll is missing from your computer. Try reinstalling the program to fix this problem.”. At that time, copying asan_rtl.dll file to chrome directory fixed the problem.

Here, we don’t need to copy or download pgort100.dll file but removing Mozilla Firefox folder in Program Files and reinstalling Firefox will do.

Fixing firefox.exe – System Error & couldn’t load XPCOM errors

1. Download Firefox full installer from Mozilla website in another browser and save to hard drive.

2. Now Navigate to “C:\Program Files” for 32-bit or “C:\Program Files (x86)” in 64-bit Windows, select and permanently delete “Mozilla Firefox” folder with the Shift +Del key combination.

3. Now Reinstall Firefox with setup file you’ve downloaded before, if you start Firefox now it will be launched without any errors.

Fix Firefox’s Error ‘The bookmarks and history system will not be functional because ..’

Note: You don’t need to worry about installed extensions, plugins, bookmarks and other data while deleting Mozilla Firefox folder because Firefox profile folder will be kept in a separate location from the installed Firefox directory. So deleting Firefox folder no way affects your profile data.