I don't think forum volunteers yet know the cause or remedy for this problem. However, know that dozens of people are reporting the same thing in recent hours, so it may be due to a rolling update gone wrong.

PS. I followed the instructions to download a new version (of Adblock Plus) and it's saying "download failed. Please check your connection. This connection is fine -

All this has started in the last week. It seems to have begin when I got rid of that unwanted Pocket by following your instructions.

PPS Same with YouTube Adblocker. Response from one volunteer (Jscher 2000) indicates that this is not isolated to me - he says "I don't think forum volunteers yet know the cause or remedy for this problem. However, know that dozens of people are reporting the same thing in recent hours, so it may be due to a rolling update gone wrong. "

Thanks jscher - and although this doesn't solve the problem for me I think the fact that it is hitting others is a first step toward a solution.

It looks like a certificate used to sign many popular extensions expired. (The verification process checks that certificate.) I don't know how soon re-signed versions of those extensions will become available, or whether another workaround will be discovered.

Exactly the same problem here that started this evening. ALL extensions including LastPass, Blur, Avast Security and half-dozen others all gone. No way to restore them either with the same reported "Download failed" rubbish. Have had to switch to Edge, which I really don't care for. Tried calling their customer service number, but there was no answer, so apparently they don't have 24/7 support.

Hi MarcLewis, Mozilla doesn't have phone support. Not sure who you called, but probably a good thing they didn't answer!

Same thing happened to me today. Any solutions yet?

There is a hotfix released for the issue about an expired intermediate certificate that caused extensions to get disabled that is currently applied via a shield study and you only get this hotfix when studies are enabled.

• Options/Preferences -> Privacy & Security -> "Data Collection and Use"

See also:

• https://support.mozilla.org/en-US/kb/add-ons-disabled-or-fail-to-install-firefox
• https://blog.mozilla.org/addons/2019/05/04/update-regarding-add-ons-in-firefox/

Problem solved. Many thanks for the good work, and your volunteering. I wish the for-profit companies worked as well.