Old versions of Java have been blocked - update and unblock Java

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  • Revision id: 23050
  • Created:
  • Creator: Michael Verdi
  • Comment: Fixed markup, removed blocklist info for Mac since it's not blocklisted yet. Should be easy to update when this changes. Last section can be removed the evening of April 5
  • Reviewed: Yes
  • Reviewed:
  • Reviewed by: Verdi
  • Is approved? Yes
  • Is current revision? No
  • Ready for localization: No
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Firefox recently added older versions of the Java plugin to its blocklist causing it to be disabled. This was done because the old versions are vulnerable to an attack which could take over your computer without your knowledge and access files or steal critical information like banking credentials. This article describes the steps to update Java and get it working again.

Old versions of the Java plugin are vulnerable to an attack which could take over your computer without your knowledge and access files or steal critical information like banking credentials. This article describes the steps to update Java and get it working again.

Update Java

Firefox only blocks vulnerable versions of Java so the thing to do is to update to latest version. Unfortunately, simply installing a new version of Java doesn't necessarily remove older Java versions from your computer which will leave you vulnerable. So you'll have to uninstall any old versions of Java before going ahead with the update.

  1. Go to the Java download page and download the latest Java installer but don't run it yet.
  2. Click the Firefox menu Fx89menuButton and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu Fx89menuButton and select Quit.
  3. From the Start Menu in the Windows taskbar, select Control Panel. The Control Panel opens.

    Open Windows 7 Control Panel
  4. Open the Windows program listing.
    • (Windows Vista/7) Click Programs and then Programs and Features.
    • (Windows 2000/XP) Double-click Add or Remove Programs.
  5. From the list of currently installed programs, select any Java or Java Runtime programs.
  6. To begin the uninstall:
    • (Windows Vista/7) Click Uninstall at the top of the window.
    • (Windows 2000/XP) Click Remove on the right of the Java listing.
      Note: Complete the uninstall process before proceeding.
  7. Run the installer you downloaded in step 1.
  8. Start Firefox

Java should now work as expected.

Firefox only blocks vulnerable versions of Java so the thing to do is to update to latest version.

  1. Go to the Java download page and download the latest Java installer.
  2. Click the Firefox menu Fx89menuButton and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu Fx89menuButton and select Quit.
  3. Run the installer you downloaded in step 1.
  4. Start Firefox

Java should now work as expected.

The thing to do is to update to latest version.

  1. Click the Firefox menu Fx89menuButton and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu Fx89menuButton and select Quit.
  2. From the Apple menu, select Software Update....
  3. Select the Java update and click Install. Wait for the update to complete.
  4. Start Firefox

Java should now work as expected.

If you had previously selected Disable in the blocking dialog, you may need to enable Java again:

  1. Click the menu button Fx89menuButton, click Add-ons and themesExtensions and themes and select Plugins.
  2. Find the Java Platform or Java Runtime item and click Enable.

Working around the blocklist

If you are unable to update Java and it's critical for you to continue using it, you can re-enable the blocked version.

Warning: This leaves you vulnerable to attacks. Simply browsing to a compromised website could result in your computer being exploited.

Enabling Java

  1. Click the menu button Fx89menuButton, click Add-ons and themesExtensions and themes and select Plugins.
  2. Find the Java Platform or Java Runtime item and click Enable.

If there isn't an Enable option, you can fix it by doing the following:

  1. Open your profile folder:

    • Click the menu button Fx89menuButton, click Help and select More Troubleshooting Information.From the Help menu, select More Troubleshooting Information. The Troubleshooting Information tab will open.
    • Under the Application Basics section next to Profile FolderProfile Directory, click Open FolderShow in FinderOpen Directory. A window will open that contains your profile folder.Your profile folder will open.Your profile directory will open.
    Note: If Firefox displays an error after clicking Open Folder or if you are unable to open or use Firefox, follow the instructions in Finding your profile without opening Firefox.

  2. Click the Firefox menu Fx89menuButton and select Exit.Click the Firefox menu at the top of the screen and select Quit Firefox.Click the Firefox menu Fx89menuButton and select Quit.
  3. In the profile folder that you opened earlier, find blocklist.xml (this may be listed as a "XML document" called blocklist) and pluginreg.dat (this may be listed as a "DAT document" called pluginreg). Delete both these files.
  4. Start Firefox
  5. You will be presented with the Add-ons may be causing problems window with Java listed. Uncheck the Disable box and click Restart Later.

You should now be able to use the older, insecure version of Java.