It’s possible that there is a problem with the file(s) that store the extensions registry.

Type about:support in the address bar and press enter.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Linux: Under the page logo on the left side, you will see Application Basics. Under this find Profile Directory. To its right press the button Open Directory.

Delete all extensions* files and compatibility.ini in the Firefox profile folder to reset the extensions registry.

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

After, restart Firefox.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions

• https://support.mozilla.org/kb/Unable+to+install+add-ons

+++++++++++++++++++++++++++ You will have to approve the updating one last time.

Hmmm, i tried what you suggested, see attached photo for end result. My addons are still functioning even though every add submenu displays as you see it...

My expertise isn't great in tampering with the entrails of a computer, but what you suggested, I was able to do (deleted 3 files) but what you see is after I restarted FF. I had no probs with the previous version of FF (64.0.2, if I recall) am I am fairly zealous in ensuring I use the latest versions of my software... Doesn't always work well Peter

Type chrome://mozapps/content/extensions/extensions.xul?<enter> in the address bar.

Is everything listed? Anything you don't know what it is?

Not a thing, looks exactly the same as the photo

And yet I do have several functioning extensions. The theme I got rid of by installing another then immediately removing it, thus reinstalling the default

Here's a more complete picture... not much to look at

If you haven't tried it yet, Reboot the computer.

Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

Note that all add-ons will be disabled. I want to see if the manager now shows them.

What a delight! yes, all items show up in Safe Mode, but promptly disappear when restarted in normal mode....

Just reading what that will mean for me: testing all my extensions, themes etc... take a deep breath. It's more the time element that is so problematic.....

Step 1: disabled all extensions, restarted FF, everything remains empty, so it's not the extensions... next I need to tackle the themes, but in safe mode they are all listed as disabled. And, of course, in normal mode, nothing appears... So I might have to remove them all...

And removing all themes (except of course the 2 that can't seem to be removed, the default light & dark FF themes) produced a null result. So, I'll go back and turn my extensions on in Safe Mode

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes). If the problem goes away, that tells us one thing. If it does not, that tells us something else.

It could be Hardware Acceleration. How to disable Hardware Acceleration {web link}

Did as instructed (once I read the correct version instructions... need more caffeine) and no difference, all fields still blank

BTW, thanks for helping me out, though we have got no positive results, I hope the negatives gives you some idea, 'coz I got nuthin. It worked the previous version, but doesn't in this one is the only (almost useless) clue I can offer

Do you see extensions listed on the "Help -> Troubleshooting Information" (about:support) page?

Yes I do. Here (I hope) they are pasted from that section:

Extensions Name Version Enabled ID Adblock Plus - free ad blocker 3.4.3 true {d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d} Awesome RSS 1.3.5 true {97d566da-42c5-4ef4-a03b-5a2e5f7cbcb2} Browsec VPN - Free and Unlimited VPN 3.21.12 true browsec@browsec.com Download Manager (S3) 5.10 true s3download@statusbar Feedbro 3.39.0 true {a9c2ad37-e940-4892-8dce-cd73c6cbbc0c} FoxClocks 5.1.5 true {d37dc5d0-431d-44e5-8c91-49419370caa1} IDM Integration Module 6.32.3 true mozilla_cc3@internetdownloadmanager.com Livemarks 1.16 true {c5867acc-54c9-4074-9574-04d8818d53e8} SaveMyTabs 1.0.1 true {b01c009f-102b-46b1-970d-2e120483b63a} Britannica Insights 3.8 false {4a2c8133-4ad1-421b-9e77-b517a8a4e34b} Bulk Media Downloader 0.2.1 false {72b2e02b-3a71-4895-886c-fd12ebe36ba3} eBay for Firefox 5.3.0 false {62760FD6-B943-48C9-AB09-F99C6FE96088} Foxit PDF Creator 9.2.0.0 false FireFoxNew-WebExtensions@foxitsoftware.com Norton Safe Web 3.4.0.4 false nortonsafeweb@symantec.com Theme Font & Size Changer 62.0 false {f69e22c7-bc50-414a-9269-0f5c344cd94c}

This is probably not relevant, but after updating to FF65, I added an extension which I promptly removed. My tabs don't look as nice as they did in FF64, so I tried Colored Tabs Extension. How interesting! Immediately, each tab would cycle through all the other tabs that were open, with probably <1/4 sec each tab view... Chaos is an understatement, so I promptly removed it and FF settled down from the mangled hyperactivity. That's the only venture into changing FF after FF65 installed. And moving the tabs below the address bar. A separate issue which Mozilla insists on doing things the way they like it rather than what the user wants. A wee grumble. Regularly expressed lately, sadly.

See this thread for updated userChrome.css code for Firefox 65 to move the tabs to the bottom position.

• /questions/1248277 Reposition Tabs at bottom, directly above web page in Firefox 65.0?

Thanks for that. Yep, I got that sorted within minutes of installing FF65... I just added that note of what I had done it in case anything in the mix may be responsible for the blankness of my add ons/themes/extensions menus

I am starting to think the problem is with the page writing white on white. That is why Safe Mode shows the list.