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.

Avatar for Username

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

Cuireadh an snáithe seo sa chartlann. Cuir ceist nua má tá cabhair uait.

I cannot install an add-on

  • 2 fhreagra
  • 1 leis an bhfadhb seo
  • 14 views
  • Freagra is déanaí ó RetiredAF

RetiredAF
RetiredAF
more options

I am attempting to install an add-on. When I click on it I get a prompt that says "this add-on requires Firefox 4.0 and you are using Firefox 3.6.8"

I have downloaded and installed Firefox 4.0. When I go to "About Firefox" it indicates that I am using Firefox 4.0.1. However this add-on still will not install.

I have uninstalled and reinstalled Firefox 4.0 several time but nothing seems to work. I did get it to install and run on my laptop computer with no problem. The laptop is running Windows 7.

This computer is running Windows Vista.

I am attempting to install an add-on. When I click on it I get a prompt that says "this add-on requires Firefox 4.0 and you are using Firefox 3.6.8" I have downloaded and installed Firefox 4.0. When I go to "About Firefox" it indicates that I am using Firefox 4.0.1. However this add-on still will not install. I have uninstalled and reinstalled Firefox 4.0 several time but nothing seems to work. I did get it to install and run on my laptop computer with no problem. The laptop is running Windows 7. This computer is running Windows Vista.

Réiteach roghnaithe

This is typically caused when an add-on changes the user agent string (identifies the version of Firefox). To rectify this you can reset your user agent string.

  1. Type about:config into the location bar and press enter
  2. Accept the warning message that appears, you will be taken to a list of preferences
  3. Locate the preference general.useragent.override, right-click on it and select Reset, this will set the user agent string back to the default in Firefox 4

There are other user agent string settings that may have been modified, but these are no longer used in Firefox 4. You can reset them if you want, for details see https://support.mozilla.com/kb/Websites+or+add-ons+incorrectly+report+incompatible+browser

Read this answer in context 👍 0

All Replies (2)

TonyE
TonyE
  • Moderator
more options

Réiteach Roghnaithe

This is typically caused when an add-on changes the user agent string (identifies the version of Firefox). To rectify this you can reset your user agent string.

  1. Type about:config into the location bar and press enter
  2. Accept the warning message that appears, you will be taken to a list of preferences
  3. Locate the preference general.useragent.override, right-click on it and select Reset, this will set the user agent string back to the default in Firefox 4

There are other user agent string settings that may have been modified, but these are no longer used in Firefox 4. You can reset them if you want, for details see https://support.mozilla.com/kb/Websites+or+add-ons+incorrectly+report+incompatible+browser

RetiredAF
RetiredAF Úinéir na ceiste
more options

TonyE, you are da man! That worked like a champ. Thanks so much.