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unable to install add on

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  • 1 has this problem
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  • Last reply by EP1952

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I had to reinstall my antivirus (Gdata), since this all my add ons are not working. I tried to reinstall, but did not help. Then I reinstalled firefox completely, but now I can not install any add on (lastpass, ghostery, belgium eid). Or I get the message : add on is corrupt. Or I get the message: no connection When I swith off Gdata, also then I can't install add on. Win 10 - Firefox 66.0.3 (64-bits

I had to reinstall my antivirus (Gdata), since this all my add ons are not working. I tried to reinstall, but did not help. Then I reinstalled firefox completely, but now I can not install any add on (lastpass, ghostery, belgium eid). Or I get the message : add on is corrupt. Or I get the message: no connection When I swith off Gdata, also then I can't install add on. Win 10 - Firefox 66.0.3 (64-bits

Chosen solution

This Add-on problem seems to be on all 52...66 Firefox versions. You can not install any Add on from web, and not even from your own hard disk.

I found a stupid, old-time work-around to this problem, but at it works and solves this immediately.

Turn your computer clock backwards some days, like May 1 2019 or something.

Then you can immediately re-install all your add-ons again. After I turned the clock back to original Date, the Add-ons still remain and are working.

I have to do some more testing, if the problem will come back. I just wanted to share my findings this far.

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All Replies (3)

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hi EP1952, please see the banner at the top of the support page - unfortunately there's a technical issue (an expired certificate used for addon verifications) today.

mozilla is already rolling out a hotfix for this problem, using the studies system. you can check if you have studies enabled:

  1. Go to [=] > Options > Privacy & Security.
  2. Make sure Allow Firefox to install and run studies is check marked.

if you had the preference disabled, reenable it temporarily and restart the browser. after your add-ons have been re-enabled you can disable the setting again.

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Chosen Solution

This Add-on problem seems to be on all 52...66 Firefox versions. You can not install any Add on from web, and not even from your own hard disk.

I found a stupid, old-time work-around to this problem, but at it works and solves this immediately.

Turn your computer clock backwards some days, like May 1 2019 or something.

Then you can immediately re-install all your add-ons again. After I turned the clock back to original Date, the Add-ons still remain and are working.

I have to do some more testing, if the problem will come back. I just wanted to share my findings this far.

more options

I do not know how, but suddenly all add ons are working again.