Hi MarkTedrow, you haven't heard?

A critical certificate Firefox uses to verify extension signatures expired at midnight May 4th (GMT). The first time your Firefox runs its daily signature verification, most fail and those extensions are disabled. Your Firefox needs an updated certificate installed.

Currently there are updates for Firefox 60 ESR and Firefox 66. There was a note on Twitter that Mozilla may release something for unsupported older versions. We don't know about any schedule for that yet.

For the time being, you would need to install the new certificate for verifying extension signatures a different way, such as installing manually. For an unsupported approach, see: https://support.mozilla.org/questions/1258165#answer-1218833

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.

Mozilla Blog Post Update:
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).
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.
(May 5, 16:25 EDT)

~Pj

Am I going to lose my add-ons with your update like I did on Firefox Quantum? This is why I went back to version 52 and turned auto update off. I need all of my add ons.

I will be happy to update as long as my add ons are not removed.

Hi MarkTedrow, you already know the answer: "legacy" extensions do not run in Firefox 57 or later, and Firefox 66 is no exception.

I did get a better version of Firefox Quantum than I did before but I still am not happy about losing some legacy Add-ons that I used. One of the biggest was Unmht and Mozilla Archive Format that I used for YouTube. I used Mozilla for my YouTube because they had better Add-ons than anyone else.

I would use another add-on but there is nothing for mime html. I simply want to be able to save as MHTML. I have even tried Installing extensions from previous profiles but all they come up as now is that they cannot be installed because they appear to be corrupt so I may as well delete all of my prior profiles because now they don't work. Any other suggestions?

This is why I turned off automatic updates so I could stay at an earlier version of Mozilla so the add-ons would all work instead of being removed.

Hi MarkTedrow, I am not aware of any extensions that create or read the MHTML format. Your search probably is more up-to-date than my vague memory.

The most similar thing might be https://addons.mozilla.org/firefox/addon/save-page-we/ which embeds images into the page but saves as HTML instead of MHTML.

How did MAF (MAFF?) work with YouTube?

Don't delete all your old profiles. There are ways to use them in alternate browsers and they would be difficult to find again on the web.

Thanks for your reply. I am not familiar with Maff or what it does. I have never used it. I have downloaded "save page we" but I haven't figured it out yet. What is the difference between MTHML and HTML?

Like I said, in Mozilla I used to use the extensions Mozilla Archive Format and UNMHT. They were both great. If you can explain to me how "save page we" works, I would be grateful.

MarkTedrow said

What is the difference between MTHML and HTML?

MHTML is a format from Internet Explorer that is similar to how email messages are stored. Browsers need special code to read them.

HTML is the standard format of web pages.

MarkTedrow said

I am really frustrated. I have several long time add-ons in my Mozilla/Firefox and today about 10:30 am over half of the disappeared from my toolbar... I am using version 56.0.2 (64-bit)...

Additional Info: From Mozilla Blog:

Updates – Last Updated: 19:28 EDT May 8 2019

We’ve released Firefox 66.0.5 for Desktop and Android, and Firefox ESR 60.6.3, which include the permanent fix for re-enabling add-ons that were disabled starting on May 3rd. The initial, temporary fix that was deployed May 4th through the Studies system is replaced by these updates, and we recommend updating as soon as possible. Users who enabled Studies to receive the temporary fix, and have updated to the permanent fix, can now disable Studies if they desire.

For users who cannot update to the latest version of Firefox or Firefox ESR, we plan to distribute an update that automatically applies the fix to versions 52 through 60. This fix will also be available as a user-installable extension. For anyone still experiencing issues in versions 61 through 65, we plan to distribute a fix through a user-installable extension. These extensions will not require users to enable Studies, and we’ll provide an update when they are available.

"Updates – Last Updated: 11:51 EDT May 8 2019

Firefox 66.0.5 has been released, and we recommend that people update to that version if they continue to experience problems with extensions being disabled. You’ll get an update notification within 24 hours, or you can initiate an update manually.
An update to ESR 60.6.3 is also available as of May 8th. We’re continuing to work on a fix for older versions of Firefox, and will update this post and on social media as we have more information."

~Pj