Firefox 52 discontinues NPAPI plugin support (Java, Silverlight, etc)
Mozilla has announced that Firefox will discontinue support for Java, Silverlight and other NPAPI plugins in March 2017 with Firefox 52 with the exception of the Flash plugin. The 64-bit version of Firefox already does this, only supporting Flash. With version 52 of Firefox, due on March 7, 2017, no NPAPI plugins will be supported other than Flash. At that point, you can continue to use the Firefox Portable ESR release if you need to use NPAPI plugins like Java.