Separate Security Issue: Update your Flash Player or remove it using these links; Uninstall Flash Player | Windows {web link} Uninstall Flash Player | Mac {web link}

Note: Windows users should download the ActiveX for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the ActiveX.

Flash Player Version 32.0.0171

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download. <Windows Only>

https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download. <Windows Only> +++++++++++++++++++ See if there are updates for your graphics drivers https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration

Try using these links; Firefox; Extended Support Release {web link} ESR Notes System Requirements

Firefox ESR 60.6.3 May 8, 2019

Thanks, Fred. [btw, maybe your reply addresses only what I ignorantly tried to add to the "one sentence question," but posted as a reply to myself? Sorry, i'm new to this forum.]

What I'm asking is a way to jump from 52.9 (esr) to the current (v66), without a screwup, so that most add-ons can work again. I didn't see a yea/nay as to simply downloading a current v66 installer and running it, --or is other preparation needed?

There's no means to just fix the expired cert in 52.9 esr, I gather (to allow add-ons to validate)? Also, trying the button to "Download latest ESR," it only offers 52.9 again altho the info mentions v60. I'm in a blind alley now?

GuyinCM said

Windows 7/ 64 bit; (but on Help site I keep getting banner "..outdated unsupported operating system" as if I had XP or Vista. What? Confusing.)

Your useragent in More System Details by your post is Mozilla/5.0 (Windows NT 5.1; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0

The NT 5.1 is Windows XP and since you appear to have several NPAPI Plugins running in Firefox it is likely to actually be Firefox 52.9.0esr and not a modified UserAgent. You have likely been running Firefox in Windows XP compatibility mode.

Look at article and make sure you uncheck the run in Windows XP compatibility mode as this is not needed ever. This will then make the useragent show you having Windows 7 and not XP.

https://support.microsoft.com/en-ca/help/15078/windows-make-older-programs-compatible

Note Firefox since the 52.0 and later Releases have only allowed one NPAPI Plugin to run and that is Flash Player from Adobe.

Firefox 66.0.5 can be downloaded from www.mozilla.org/firefox/all/