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How do I re-enable a blocked Java Plugin?

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New User

How do I re-enable a blocked Java Plugin?

First, let me explain. I work in a support role for a company that utilizes certain element management systems to monitor and troubleshoot network faults. Due to our company's security and application support policies we are forced to use a dated version of Firefox and Java to access the EMS's webserver.

The problem: With the recent update to Mozilla's blocking policies the Java version we utilize is being blocked and access to the site no longer functions properly. We need some method of workaround that will enable us to circumvent the block.

Disclaimers ahoy: we actively and willingly acknowledge the risks that are inherent in actions such as I request. I would ask that discussion pertains to the topic as we need an immediate workaround to access our tool and a long-term -safe- solution will be cooked up with the help of our company's processes.

I am happy to provide any details that may be needed.

Thanks! EDIT: I resolved the issue myself: see reply below.

1 ACCEPTED SOLUTION

Accepted Solutions
New User

Re: How do I re-enable a blocked Java Plugin?

I solved it. Proceed at your own risk

  1. Open new Tab
  2. Navigate to about:config
  3. Accept security warning
  4. Change extensions.blocklist.enabled to false
  5. Restart browser

This prevents firefox from checking the blocklist you have configured at extensions.blocklist.detailsURL

5 REPLIES
New User

Re: How do I re-enable a blocked Java Plugin?

I solved it. Proceed at your own risk

  1. Open new Tab
  2. Navigate to about:config
  3. Accept security warning
  4. Change extensions.blocklist.enabled to false
  5. Restart browser

This prevents firefox from checking the blocklist you have configured at extensions.blocklist.detailsURL

New User

Re: How do I re-enable a blocked Java Plugin?

I've tried this solution and it doesn't work. The preference is marked false and it's written in italics, but java remains disabled. Could it be that java is a plugin and not an extension?

New User

Re: How do I re-enable a blocked Java Plugin?

I don't know if you're still having this problem but the last guy forgot to mention something. Once you change that string in the about:config page, you have to go to Tools > Add-ons Manager, switch to the plugins tab, and re-enable Java. The option you changed in about:config is just meant to prevent FireFox from disabling plugins in the future, not re-enable ones it's already disabled. :)

Site Moderator

Re: How do I re-enable a blocked Java Plugin?

If prefs on the about:config page show as italic then they may have been locked (Status column shows locked) and you can't change them in cases like this.

New User

Re: How do I re-enable a blocked Java Plugin?

I HIGHLY DISCOURAGE ANYONE FROM DOING THIS

THIS WILL DISABLE Firefox from checking to see if you have insecure plugins and also re-enable ANY disabled plugins, not just Java!

However, sometimes we don't get a choice.

I haven't been able to find any documentation whatsoever on how Firefox manages enabling and disabling plugins. The only place I've been able to find details is inside pluginreg.dat. It's a mostly human readable file, but it's automatically generated by Firefox and appears to be too complicated to parse and edit with any sort of simple script.

So what I did was the following:

  1. Follow blang1's instructions above in the first post to set extensions.blocklist.enabled to false using about:config or using a script or echo >> command to add the line user_pref("extensions.blocklist.enabled", false); to the users prefs.js file
  2. Delete blocklist.xml from their Firefox profile
  3. Delete pluginreg.dat from their Firefox profile

Make sure Firefox isn't open when you modify prefs.js directly (not using about:config) or try and remove the blocklist.xml or pluginreg.dat or they will just get re-written unmodified when Firefox closes down.

When Firefox starts the next time it will automatically regenerate pluginreg.dat with Java enabled and the blocklist.xml file shouldn't be downloaded anymore to disable it again.