We're currently experiencing with add-ons. A fix is on the way. We apologize for any inconvenience caused. https://discourse.mozilla.org/t/certificate-issue-causing-add-ons-to-be-disabled-or-fail-to-install/39047

''AndrewASB [[#question-1258064|said]]'' <blockquote> </blockquote> The Forum shows your Adobe Flash Plug-in is out of date. (Version 27.x.x.xxx)<Br> You're running an older version, which can cause problems and be a '''<U>Security Risk</U>'''. <Br> If you don't use it and do not keep it updated, you can Disable or Uninstall it.<Br> Mar 12th, 2019...<Br> Latest Adobe Flash Version (32.0.0.'''171'''). <Br> In the FireFox Browser, go to '''Add-ons''' > '''Plug-ins''' and click on the '''Shockwave Flash''' Options to check the Flash version.<Br> Flash seems not to Automatically Update, so you need to keep a regular eye on these for Updates. (Flash Support will end in FireFox at some point down the road.) <Br> You can update Flash from your Anti-Virus Program's 'Software Updater' area (Avast can do this) or on Adobe's Website: <Br> https://helpx.adobe.com/flash-player.html<Br> Upon having an older version, go to step 2 on Adobe's site (the link referenced above) to download the latest version:<Br> Note : UnCheck the boxes for the additional sponsored software that is offered on the download page if you do not want it also installed.<Br><Br> <Hr> There was a Bug-A-Boo with a Certificate Expiration Date dealing with the Add-ons. There's a new FF Version with the main Fix, '''66.0.4'''. <Br> <Br> [https://blog.mozilla.org/addons/2019/05/04/update-regarding-add-ons-in-firefox/ Mozilla Blog Post Update]: <Br> <B>A Firefox release has been pushed — version 66.0.4 on Desktop and Android, and version 60.6.2 for ESR. This release repairs the certificate chain to re-enable web extensions, themes, search engines, and language packs that had been disabled (Bug 1549061).<Br> There are remaining issues that we are actively working to resolve, but we wanted to get this fix out before Monday to lessen the impact of disabled add-ons before the start of the week. More information about the remaining issues can be found by clicking on the links to the release notes above. <Br> (May 5, 16:25 EDT)</B> ~Pj