Tap here to go to the mobile version of the site.
Your Firefox is out of date and may contain a security risk! Upgrade Firefox

Support Forum

browser.pagethumbnails.capturing_disabled - should be set to false. Check https://developer.mozilla.org


Most sites make a lot of noise about browser.pagethumbnails.capturing_disabled - and they repeat just one after another that this should be set to "true" to prevent thumbnail storage. But when you look at the right source, like: https://developer.mozilla.org/en-US/docs/Mozilla/Preferences/Preference_reference/browser.pagethumbnails.capturing_disabled

true (default)

   The application creates screenshots of visited web pages.


   The application doesn't create screenshots of visited web pages. 

The name of the parameter is confusing. But it seems that it should be set to "false" to prevent thumbnail storage. And the right question should be about reading abilities ;) But I will ask another one - does Mozilla will try to conntact with those sites and say them that they are wrong? Have a nice day folks! :)

Additional System Details

Installed Plug-ins

  • Next Generation Java Plug-in 10.9.2 for Mozilla browsers
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • 5.1.10411.0
  • Shockwave Flash 11.1 r102
  • DevalVR 3D Plugin 0,8,2,2
  • Adobe PDF Plug-In For Firefox and Netscape 8.3.1
  • DevalVR 3D Plugin 0,8,1,0
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • NPFxFoto.DLL
  • Picasa plugin
  • Windows Presentation Foundation (WPF) plug-in for Mozilla browsers
  • np-mswmp
  • DjVu Plug-In(external version
  • Adobe PDF Plug-In For Firefox and Netscape
  • RealPlayer(tm) LiveConnect-Enabled Plug-In
  • DRM Netscape Network Object
  • Npdsplay dll
  • DRM Store Netscape Plugin
  • Office Plugin for Netscape Navigator


  • User Agent: Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/17.0 Firefox/17.0

More Information

  • Top 10 Contributor
2365 solutions 20922 answers

Firefox has a mix of preferences saying "enabled" or "disabled" and of course true and false have the opposite effect depending on which you're changing. Since this one has "disabled" in the name, "true" definitely should disable the thumbnails and therefore the documentation would be incorrect on MDN.

When I look at the source code (browser-thumbnails.js lines 34-36), it seems that "true" would completely bypass the capturing of new thumbnails and the updating of old ones. Not sure it would clear the ones already saved.

Have you tested to confirm?

  • Top 10 Contributor
  • Moderator
10751 solutions 96757 answers

Helpful Reply

You will have to delete the Thumbnails folder in the Firefox Profile Folder to remove already stored thumbnails.
The pref only prevent new thumbnails from getting generated.

Cartel 0 solutions 6 answers


Modified by Cartel

  • Top 10 Contributor
2365 solutions 20922 answers

Helpful Reply

Hi Cartel, the last two posters in that thread said it worked for them. Which posts were you referring to?

Also, could you use a more family friendly avatar for this forum?