Do anyone have a fix for this

Did you contact the Addon devs about the installation issue?

Hi, this is a problem with older versions of Firefox. They do not have the latest certificate to verify extension signatures, so they all look invalid after 3/14/2025. Ref. Update Firefox to prevent add-ons issues from root certificate expiration

Your Firefox reported itself to be version 115, so if you update a bit you should get there. You need at least Firefox 115.13.0esr, and the current release in the series is 115.21.0esr. You can try either:

• Built-in updater: Update Firefox to the latest release
• Download and run installer: https://www.mozilla.org/firefox/all/desktop-esr/ => make sure to select 115 for Windows 7, not 128

Success?

After updating, Firefox will still be waiting until tomorrow, typically, to check and re-enable your extensions. To speed that up:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

More info on about:config: Configuration Editor for Firefox. The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.

(2) In the search box in the page, type or paste xpi-signature-verification and pause while the list is filtered

(3) Click the trash can at the right end of the row for the app.update.lastUpdateTime.xpi-signature-verification preference to remove this preference

(3) Do a normal exit/restart of Firefox, and within about a minute Firefox should reverify your extensions.

I like this old version of Firefox. Only 2 days ago it turned off the Adblocker so they must have done an updates which triggered this Adblocker to get disabled.

Anyway if I can’t find a solution I might have to try a different browser. Also I do not like the blue screen in private window in their latest version

What's your precise current version? You can find that in the first table on the Troubleshooting Information page:

Use the Troubleshooting Information page to help fix Firefox issues

The latest update was 115.21.0esr.

In order to verify extensions, you need at least 115.13.0esr.

These are still Firefox 115, but with bug fixes applied. You can check the release notes to see what has been changing: https://www.mozilla.org/firefox/releases/ (you can scroll down or use Ctrl+F to find 115)

Did you contact the Addon devs about the installation issue?

That is not the issue if you paid attention to the replies in other similar threads you posted in.

I like this old version of Firefox. Only 2 days ago it turned off the Adblocker so they must have done an updates which triggered this Adblocker to get disabled. Anyway if I can’t find a solution I might have to try a different browser. Also I do not like the blue screen in private window in their latest version

What Firefox 115.x.0 esr version are you using as the extensions would only be disabled if you are using 115.12.0esr or older. You need 115.13.0esr at minimum while the current update is 115.21.0esr. The older 115 ESR channel will be updated till 115.27.0esr in August unless Mozilla extends updates again.

A ESR versions only get allowed stability/security fixes and no features added as they are made for Enterprise users in mind who like longer term stability.

All the other web browsers based on Chrome/Chromium already dropped support of the EOL Windows 7, 8, 8.1 back in Jan/Feb 2023.