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I cannot install an add-on

  • 2 replies
  • 1 has this problem
  • 14 views
  • Last reply by RetiredAF

RetiredAF
RetiredAF
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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.

Chosen solution

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

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All Replies (2)

TonyE
TonyE
  • Moderator
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Chosen Solution

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