User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:55.0) Gecko/20100101 Firefox/55.0 Build ID: 20170622104007 Steps to reproduce: Firefox is my default browser. I selected a local htm page from my hard-drive which has an embedded swf Actual results: Firefox launched with the URL of file:///DriveLetter:/MyDir/myPage.htm but the flash player plugin (126.0.0.131) did not launch so the content was not displayed. FYI: If I move the files to my IIS wwwroot folder and call it via my localhost 192.168.1.2/myPage.htm - Firefox launches and flash player plug-in launches too, as expected and the content is displayed Expected results: Flash player should have launched and the content should have displayed in firefox

You can no longer load Flash from file:///. See https://www.fxsitecompat.com/en-CA/docs/2017/flash-can-now-be-loaded-only-from-http-https/ for details.