Join the AMA (Ask Me Anything) with the Firefox leadership team to celebrate Firefox 20th anniversary and discuss Firefox’s future on Mozilla Connect. Mark your calendar on Thursday, November 14, 18:00 - 20:00 UTC!

This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

XULRunner Error on Reinstall

  • 1 cavab
  • 1 has this problem
  • 1 view
  • Last reply by cor-el

more options

Windows 10 - Lenovo Thinkpad X1 Carbon This fall after an update attempt, Firefox started trying to update every time it was started. Deleted Update files in Program Data. FF would restart normally one time. Update data files were always replaced and the update on every startup continued - over and over and over. Tried refreshing FF- same thing. Uninstalled FF this AM and tried to reinstall when I get the following error:

XULRunner Error: Platform version "94.0.2" is not compatible with minVersion >= 94.0.1 maxVersion <= 94.0.1

No FF - HELP!

Windows 10 - Lenovo Thinkpad X1 Carbon This fall after an update attempt, Firefox started trying to update every time it was started. Deleted Update files in Program Data. FF would restart normally one time. Update data files were always replaced and the update on every startup continued - over and over and over. Tried refreshing FF- same thing. Uninstalled FF this AM and tried to reinstall when I get the following error: XULRunner Error: Platform version "94.0.2" is not compatible with minVersion >= 94.0.1 maxVersion <= 94.0.1 No FF - HELP!
Attached screenshots

Chosen solution

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.

You can find the full installer of the current Firefox release (94.0.2) in all languages and all operating systems here:

Read this answer in context 👍 0

All Replies (1)

more options

Seçilmiş Həll

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.

You can find the full installer of the current Firefox release (94.0.2) in all languages and all operating systems here: