Firefox ESR 52.9.0 (64-bit) will not recognize its own Flash Player plugin. Background: I'd been happily using Firefox 46 until yesterday when I got the bad idea to update to a more recent version. Chose FF 52 as it is the last version that supports my addons and themes. Unistalled 46 and installed ESR 52 (64-bit). Everything works except the Flash plugin. What happens: 1. Addons page shows that the plugin is installed. 2. Adobe's web-based version checker shows I have Shockwave Flash version 30.0.0.134 installed. 3. Shockwave Flash v. 30.0.0.134 is set to ALWAYS ACTIVATE in FF Addons page ... and no Flash player content can be played. This includes Adobe's own Flash-based tools for checking if Flash plugin is installed. They all say it is not installed and direct me to download. Tried: Uninstalling Flash plugin, rebooting, installing anew. Changing plugin activation to Ask to activate, then Always activate Changing autoplay config settings to always allow autoplay Rebooting in the emergency mode (no addons, extensions etc. -- no help) Flash Player DOES work in other Mozilla-based products (I installed Pale Moon). It basically works everywhere except in Firefox. What options do I have other than reverting to FF 46? Should I have installed a 32-bit version? I have 64-bit Win 7.