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Keep getting message "uses an invalid security certificate"; The certificate is not trusted because it was signed using a signature algorithm that was disabled

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  • Last reply by cor-el

bhaar694
bhaar694
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I can't connect with any website - not even mozilla. I get the message "uses an invalid security certificate". When I look at the technical details it says: "The certificate is not trusted because it was signed using a signature algorithm that was disabled because that algorithm is not secure. (Error code: sec_error_cert_signature_algorithm_disabled)". I get this message for any website - yahoo, google, facebook. I have uninstalled and reinstalled firefox and still have the same problem. I have started it in safe mode and the problem persists. I am using Windows 8. The problem started about a week ago but it only happened on a couple of websites. Now it is any site I try to go to. Help!!

I can't connect with any website - not even mozilla. I get the message "uses an invalid security certificate". When I look at the technical details it says: "The certificate is not trusted because it was signed using a signature algorithm that was disabled because that algorithm is not secure. (Error code: sec_error_cert_signature_algorithm_disabled)". I get this message for any website - yahoo, google, facebook. I have uninstalled and reinstalled firefox and still have the same problem. I have started it in safe mode and the problem persists. I am using Windows 8. The problem started about a week ago but it only happened on a couple of websites. Now it is any site I try to go to. Help!!

All Replies (1)

cor-el
cor-el
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  • Top 10 Contributor
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You can check the connection settings.

If you do not need to use a proxy to connect to internet then try to select "No Proxy" if "Use the system proxy settings" or one of the others do not work properly.

See "Firefox connection settings":

Try to rename the cert8.db file (cert8.db.old) and delete the cert_override.txt file in the Firefox profile folder to remove intermediate certificates and exceptions that Firefox has stored.

If that has helped to solve the problem then you can remove the renamed cert8.db.old file. Otherwise you can rename (or copy) the cert8.db.old file to cert8.db to restore the previously stored intermediate certificates. Firefox will automatically store intermediate certificates when you visit websites that send such a certificate.