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

I cannot install an add-on

  • 2 odgovori
  • 1 ima ovaj problem
  • 14 views
  • Posljednji odgovor poslao 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.

Izabrano rješenje

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

Pročitajte ovaj odgovor sa objašnjenjem 👍 0

All Replies (2)

more options

Odabrano rješenje

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

more options

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