Just so that everyone on this browser platform is wondering what in the heck is going on and why their add on extensions are being blocked, it is nothing you did.

https://techcrunch.com/2019/05/03/a-glitch-is-breaking-all-firefox-extensions/

I got hit with this earlier this evening in 52.9.0esr. Very annoying.

Setting "xpinstall.signatures.required" to false in about:config allowed the Addons to run again, but they still had nag warning messages in the Addons dialog.

24 minutes ago, LoneCrusader said:

Setting "xpinstall.signatures.required" to false in about:config allowed the Addons to run again, but they still had nag warning messages in the Addons dialog.

I tried that too, doesn't work. Apparently it has something to do with signatures of some sort. I'm surprised though that even older Firefox versions are affected this way.

Looks like users of certain forks aren't affected. Waterfox, Basilisk and Pale Moon have xpinstall.signatures.required set to false by default.

Temporary and easy fix is detailed here:  "Missing something? Some extensions are no longer supported"

Rumour is that Firefox 66.0.4 is in close to release and will fix the issue.

Edited May 4, 20197 yr by Radish

See this page direct from Mozilla on the bug and possible temporary fix;

https://blog.mozilla.org/addons/2019/05/04/update-regarding-add-ons-in-firefox/

It seems to be fixed now.
A certificate had expired apparently, which presumably nobody at Mozilla had anticipated!
I didn't have the problem with FF 52.9.1 ESR on Windows XP, but I did have it on FF 66.0.3 on Windows 10.
It was very annoying while it lasted!

I seem to be up and running again too.  Actually, I was only running FF 51 ESR on my Windows 2000 install but still didn't have my extensions working, even after I did the whole setting signatures setting to false, but I just happened to install FF 52 ESR over it and when it launched, then it all seemed to be okay.  Even though my Debian laptop that I'm using right now seems to still have an issue, saying to proceed with caution because my extensions haven't been verified to work with FF. Very strange!

@Dave-H It seems to be fixed now.
A certificate had expired apparently, which presumably nobody at Mozilla had anticipated!
I didn't have the problem with FF 52.9.1 ESR on Windows XP, but I did have it on FF 66.0.3 on Windows 10.
It was very annoying while it lasted!

it hit me on 52.9.0 around 7.30pm

is there a fix for ESR thought it was only Nightly at the moment, ESR will be last

=====================

Try this, this DOES work I have done it with success, unlike other so called fixes

Shut down Firefox
Open extensions.json
Rreplace all instances of "appDisabled":true to "appDisabled":false
Replace all instances of "signedState":-1 to "signedState":2
Save
Change extensions.json to readonly or firefox will change everything back.
start browser
Disable and re-enable all extensions in about:addon

some will have Delete icon missing most Will re-install and delete icon comes back

Make sure you set yhe json file to read only

then any that stil get not verified use the about:debugging and reload the extention

Edited May 5, 20197 yr by DrWho3000

Thanks.
My FF 52.9.1 ESR's add-ons are working fine, but still have the verification warnings on most of them on the add-ons page list.
I'll wait awhile to see if this corrects itself automatically, as there seems to be no actual loss of functionality.

And now this morning MU has taken a crack at it with KB963707.

@DrWho3000's fix made my extensions work, thanks.

Anyway, I am embarrassed by Mozilla's behaviour. i know something can sometimes break in entity as big as Mozilla, but... sigh!

Firefox 66.0.4 released now. Have installed and tested it, seems to fix the issue. Well done, Mozilla! Don't put us through that again.

https://ftp.mozilla.org/pub/firefox/releases/66.0.4/

Edited May 5, 20197 yr by Radish

3 hours ago, Radish said:

Firefox 66.0.4 released now. Have installed and tested it, seems to fix the issue. Well done, Mozilla! Don't put us through that again.

https://ftp.mozilla.org/pub/firefox/releases/66.0.4/

This actually works on XP SP3 does it I downloaded,  Firefox Setup 60.6.2esr but hesitant to install

Seems that updating to Firefox 66.0.4 might not instantly cure the problems with addons for everyone - manual intervention might be necessary. Details are in the now published Release Notes here (follow the links): https://www.mozilla.org/en-US/firefox/66.0.4/releasenotes/

6 minutes ago, DrWho3000 said:

This actually works on XP SP3 does it I downloaded,  Firefox Setup 60.6.2esr but hesitant to install

I would think it won't run on XP SP3. I couldn't actually find system requirements for 60.6.2esr but did find for 60.6.1esr Windows 7 or higher seems to be the minimum requirement for that: https://www.mozilla.org/en-US/firefox/60.6.1/system-requirements/