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Themes no longer function since auto update to firefox 20


When firefox automatically updated to version 20, it caused the themes to no longer function. They install correctly, it says the theme is enabled, but it still looks like the plain default blue. Doesn't matter what theme I use or if I try to use the personas add-on. Nothing changes the look.

Chosen solution

Make sure that you do not run Firefox in (permanent) Private Browsing mode.

  • Tools > Options > Privacy > Firefox will: "Use custom settings for history"
  • Deselect: [ ] "Always use private browsing mode"
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Additional System Details

Installed Plug-ins

  • Shockwave Flash 11.6 r602
  • Next Generation Java Plug-in 10.15.2 for Mozilla browsers
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Adobe PDF Plug-In For Firefox and Netscape 11.0.02
  • Google Update
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • A plugin to detect whether the Adobe Extension Manager is installed on this machine.
  • VLC media player Web Plugin 2.0.2
  • A plugin to detect whether the Adobe Application Manager is installed on this machine.


  • User Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:20.0) Gecko/20100101 Firefox/20.0

More Information

  • Top 10 Contributor
  • Moderator
3196 solutions 24401 answers

IMO, beating the drum of patriotism over a minor appearance issue in a web browser has nothing to do with "free speech". IMO, that is just plain asinine.

kosimov 0 solutions 4 answers

Absolutely agree with you. Never have seen such short fuses! Not to mention that a company is always "free" to change its own products, and users are "free" to use them or not. Finally, Mozilla rep already stated more than once that the "problem" was being fixed, and that it was caused by a mistake which crept into version 20 when another issue was fixed. Oh yes, one more freedom: we are all free to make human errors! That is, we are free to make mistakes. When I consider that the internet has over a billion people on it from time to time, I guess only one or two hot-tempered users isn't bad.

Keep up the good work.