User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8) Gecko/20051111 Firefox/1.5 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8) Gecko/20051111 Firefox/1.5 On my Windows XP Pro SP2 desktop, I can't install many extensions (e.g. Image Zoom 0.1.7) or themes (e.g. Qute 3.0.4), and I get a dialog box that says something like "Qute 3.0.4 could not be installed because it is not compatible with Firefox 1.5. (Qute 3.0.4 will only work with Firefox versions from 1.5 to 1.5.0.*)" Reproducible: Always Steps to Reproduce: 1. Download a theme 2. Try to install it Actual Results: Fails to install theme or extension I have quite a lot of extensions installed: AniDisable Image Zoom (grayed out) Flashblock FirefoxView ieview View Cookies Monk Links! Tabbrowser Preferences Objection Adblock Linkification SessionSaver .2 fireFTP Greasemonkey (disabled) Bookmarks Synchronizer User Agent Switcher Most of these were installed using older versions of Firefox. I started noticing this problem around version 1.0.5.
Please check the following, Type about:config into the address bar and then in the page that appears type "version". Look down the list that should appear for app.extensions.version. If this is there right click it and choose "reset" then restart firefox.
That's fixed it. Any idea how that value got set wrong? It used to contain "0.10". Presumably it was set by a really old version, so new users would never get this, just us early-adopters.
It is not anything that firefox itself would have ever set. Either you set it manually (it is used to make firefox install extensions that appear to be for older versions), or its possible that an extension set it, though I've never heard of one that does that. Resolving invalid,
OK, I accept that that is a possibility.