Old programs, whatever they are, can become blacklisted for mostly security issues. Bypassing this could be bad for your system.

Are you having trouble with flash?

You are also an old version of Firefox. Is there a reason?

This is not an answer to my question. Please answer the question as asked.

1. Delete the blocklist.xml file in the Profile folder. 2. Start Firefox without an internet connection. 3. A new empty blocklist.xml file will be created. 4. Lock that new file so that a new set of data can't be downloaded.

Mozilla would not have been adding most versions of Flash Player to the blocklist since Dec 2014 if not for most of the versions since being affected by critical security vulnerabilities since. Otherwise there would not be any Flash Player versions on blocklist still since Feb/Mar 2013 if the security concerns were still minor.

James, The work I am doing demands that browsers can operate freely with various versions of Flash as well as other software, plug-ins, etc.

Thank you edmeister.

The version of Firefox I'm using (43.0.1) didn't make a new blocklist at all once the two that were there were deleted. Nothing to lock. Just as good.