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Change "Cannot be found" page in Firefox [advanced]


Eriksrocks's Avatar
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Member with 2,183 posts.
Join Date: Aug 2005
Location: Minnesota
Experience: Advanced
17-Feb-2006, 04:49 PM #1
Change "Cannot be found" page in Firefox [advanced]
This is a pretty complicated process, but if you really want to change that current page, follow the steps below...
  1. First, you have to close all Firefox windows, so you might want to print out these directions. For this process we are going through, you will need an unzipping utility. If you don't already have one, you can download the trial of WinZip here, or you can download the free ZipGenuis utility here.
  2. To start, navigate to the folder C:\Program Files\Mozilla Firefox\chrome. Before we start disecting Firefox, copy the file toolkit.jar and rename it toolkit.jar.old. Now, using your unzipping utility, unzip the file toolkit.jar (not toolkit.jar.old) to the desktop or your folder of choice.
  3. Inside the folder you unzipped it too, navigate to \content\global. You should see a bunch of files and several folders. Look for the file netError.xhtml. When you find it, right-click on it and go to Open With > and choose Wordpad. Replace the entire contents with this:
    HTML Code:
    <?xml version="1.0" encoding="UTF-8"?>
    <html xmlns="">
        <title>Page cannot be reached</title>
        <link rel="stylesheet" href="chrome://global/content/customerror.css" type="text/css" media="all" />
    <!-- All body content STARTS HERE! -->
    <!-- All body content ENDS HERE -->
    Put all of your "body" HTML inbetween the two comment tags. Note that if you need to reference any other files, such as images, in the file above, you will need to use this format:
    You will also need to place the files in the same directory as netError.xhtml. Save and close the file.
  4. Now we need to make just one more file. Create a file named customerror.css in the same directory as netError.xhtml. Open the file in Notepad or Wordpad, and paste the following contents into it:
    HTML Code:
    body {
      font: Verdana;
    Save the file. If you want custom CSS, the just put your custom CSS in the file above.
  5. Time to zip up! Now, using your zip utility, zip the contents of your folder into the file toolkit.jar. Replace your new toolkit.jar with the old one in C:\Program Files\Mozilla Firefox\chrome.
  6. Now test it, and hope it works.

If something goes majorly wrong with this tutorial, you can always rename the current toolkit.jar file to and rename toolkit.jar.old to just toolkit.jar. This will restore the original settings.
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