An error message about XPCOM missing or about platform version usually happens because of a failed Firefox update that left you with a mixture of old and updated files in the Firefox program folder. This can happen in case security software was keeping a handle of some of the files in the Firefox program folder preventing Firefox from replacing all the files. You need to do a clean reinstall and remove the Firefox program folder to ensure that all files are replaced. You may have to disable security software temporarily in case the problem persists.

• https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

Thank you for the information. I have successfully reinstalled Firefox but my real concern is losing all my bookmarks and passwords. I have tried to recover but can't find them anywhere. Thoughts/suggestions/help?

Thanks.

You can check this article.

• https://support.mozilla.org/en-US/kb/recover-user-data-missing-after-firefox-update
• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

You can check if you have an "Old Firefox Data" folder on the desktop in case the Refresh feature in Firefox has been used and a new profile has been created.

• https://support.mozilla.org/en-US/kb/reset-firefox-easily-fix-most-problems