Mozilla take security very seriously and this is why they do not allow any older, obsolete plug-ins or add-ons to work in Firefox by default. So if you have an older version of Adobe Flash or Oracle Java runtime environment installed, Firefox will simply block them from being used. This is done to ensure that no attack or malicious site can take the advantage of known vulnerabilities from these add-ons and plug-ins. But sometimes we really need to use these obsolete add-ons to have some work done on certain websites. This is especially true for the time duration when newer version of a plug-in has not been released and the older vulnerable plug-in has been blocked by Firefox.
One of the ways to unblock certain plug-ins and extension is by editing the blocklist.conf file in Firefox’s program folder. But why take such an ardent step when you can temporarily disable Firefox’s blocking feature for a few seconds from the Firefox configuration. Here is how:
- Open Mozilla Firefox web browser, type about:config in the address bar and press Enter. You will be shown a warning but you can continue by clicking on the I’ll be careful, I promise button.
- On the Firefox configurations web page, type extensions.blocklist in the search box to narrow down the settings we are interested in.
- Double-click on extensions.blocklist.enabled setting to change its value from true to false.
- Restart Firefox and now you can use whatever plug-in or extension that you wanted to use.
- After having used the extension or plug-in you should change the value of extensions.blocklist.enabled back to true to stay on the safer side.
Conclusion: In urgent cases if you have to use a blocked plug-in or extension in Mozilla Firefox, then you can temporarily unblock them and use them through the Firefox configurations. But they should not be blocked permanently and should never be used on insecure or unknown web sites.