Firefox 16.0.1 disables FF 3 Theme for FF 4+, how to fix

[Salmon Trout]

Find your Firefox Profile folder for example by clicking Help, Troubleshooting Information, and the Show Folder button by "Profile folder" (will open in Explorer)

Under that folder will be a folder named extensions

For each theme you have installed there will be an .xpi file

The one for my "Firefox 3 Theme for Firefox 4+ 2.0.1" is called "[email protected]". The other FF 3 theme I know about is "Firefox 3 Aero Theme For Firefox 4+ 2.0.1" and the .xpi file is called "C:\Users\Mike\AppData\Roaming\Mozilla\Firefox\Profiles\k65vu6mr.default\extensions\[email protected]"

The xpi file is a Zip file. Open it in Winzip or whatever you use.

In the topmost folder in the archive is a file called install.rdf

Drag (extract) install.rdf out somewhere and edit it in e.g. Notepad changing the max_version value to something more than 16.0.1 (I made mine 20.0)

Save the edited version and then drag it into the xpi file while it is open in your Zip program, choosing to replace the one that is already there.

Close and restart Firefox and you should see the theme is now available to be enabled.

(Below is the install.rdf for Firefox 3 Theme for Firefox 4+ 2.0.1)

<?xml version="1.0"?>
<RDF:RDF xmlns:RDF="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:em="http://www.mozilla.org/2004/em-rdf#">
   <!-- Define target application(s) that the extension can be installed in, with minimum and maximum supported versions -->
   <RDF:Description RDF:about="rdf:#$Ik7kN2">
      <!-- Describes Firefox -->
      <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
      <em:minVersion>4.0</em:minVersion>
      <em:maxVersion>20.0</em:maxVersion>
   </RDF:Description>
   
   <!-- Define our extension -->
   <RDF:Description RDF:about="urn:mozilla:install-manifest">
      <!-- Extension's ID and type -->
      <em:id>[email protected]</em:id>
      <!-- Types: 2=Extensions, 4=Themes, 8=Locale, 16=Plugin, 32=Multiple Item Package -->
      <em:type>4</em:type>
      
      <!-- Extension's info and metadata -->
      <em:name>Firefox 3 theme for Firefox 4+</em:name>
      <em:version>2.0.1</em:version>
      <em:description>Experience all the benefits of Firefox 4 (or later) with the colorful toolbar goodness of Firefox 3!</em:description>
      <em:creator>Jeremy Morton</em:creator>
      <em:homepageURL>http://ffaddons.game-point.net/ff3ff4/</em:homepageURL>
      <!-- internalName must match the 'skinname' part of the relevant chrome.manifest directives in order for those mappings to be associated with this skin. -->
      <em:internalName>ff3ff4</em:internalName>
      <!-- Allow lightweight themes / personas to apply to this theme, using 'skinnable' -->
      <em:skinnable>true</em:skinnable>
      
      <!-- Target at Firefox -->
      <em:targetApplication RDF:resource="rdf:#$Ik7kN2"/>
   </RDF:Description>
</RDF:RDF>

[Allan]

I use the CheckCompatibility extension and it works fine.

[Salmon Trout]

I use the CheckCompatibility extension and it works fine.

Could you post a link to that? It sounds useful.

What happened was: Firefox offered (today Oct 13) to update itself to 16.0.1 and advised me that the Firefox 3 themes for FF 4+ were being disabled due to incompatibility with 16.0.1. Would that extension have let me avoid that, and the workaround I was forced into?

[Allan]

Here you go: https://addons.mozilla.org/en-US/firefox/addon/checkcompatibility/

When I upgraded to FF 16 I just had to click on"Enable" for the FF3 compatibility theme in Add-Ons

[Salmon Trout]

So, it seems that when a newly updated Firefox checks an extension for compatibility it just looks for a magic number in a file. It doesn't do any kind of deep inspection of the extension. I forgot to mention that the install.rdf max version which I altered was originally 16.0.a1, the first 16.0 alpha released on 5 June 2012. Presumably this was the latest version the extension developer had tested it with. Speaking of alpha versions, I see 19.0.a1 came out on Oct 9.

[patio]

Mr Tech Toolkit...

This is what i use...lots more handy options and switches as well as the addon notification switch...

[Salmon Trout]

Mr Tech Toolkit...

This is what i use...lots more handy options and switches as well as the addon notification switch...

Not available for Firefox 16.0

[Allan]

Unfortunately Mr Tech Toolkit hasn't been available for a while now.