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Posted instructions on resolving 'Error code: SEC_ERROR_UNKNOWN_ISSUER' does not work in my new Windows 10 computer.

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  • Last reply by cor-el

DM_Young
DM_Young
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After uninstalling (using Control Panel) and re-installing Mozilla Firefox four times, I continue getting, "The owner of www.mozilla.org has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website.

"Learn more…

"Report errors like this to help Mozilla identify and block malicious sites

"www.mozilla.org uses an invalid security certificate. "The certificate is not trusted because the issuer certificate is unknown. The server might not be sending the appropriate intermediate certificates. An additional root certificate may need to be imported. Error code: SEC_ERROR_UNKNOWN_ISSUER Error code: SEC_ERROR_UNKNOWN_ISSUER."

In addition, the Tool Bar has disappeared.

Computer: Dell 32522, Software: Windows 10 and Windows Defender.

Thank you.

After uninstalling (using Control Panel) and re-installing Mozilla Firefox four times, I continue getting, "The owner of www.mozilla.org has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website. "Learn more… "Report errors like this to help Mozilla identify and block malicious sites "www.mozilla.org uses an invalid security certificate. "The certificate is not trusted because the issuer certificate is unknown. The server might not be sending the appropriate intermediate certificates. An additional root certificate may need to be imported. Error code: SEC_ERROR_UNKNOWN_ISSUER Error code: SEC_ERROR_UNKNOWN_ISSUER." In addition, the Tool Bar has disappeared. Computer: Dell 32522, Software: Windows 10 and Windows Defender. Thank you.

All Replies (1)

cor-el
cor-el
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  • Top 10 Contributor
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You can check if there is more detail available about the issuer of the certificate.

  • click the "Advanced" button show more detail
  • click the blue SEC_ERROR_UNKNOWN_ISSUER message to show the certificate chain
  • click "Copy text to clipboard" and paste the base64 certificate chain text in a reply

If clicking the SEC_ERROR_UNKNOWN_ISSUER text doesn't provide the certificate chain then try these steps to inspect the certificate.

  • open the Server tab in the Certificate Manager
    • Options/Preferences -> Privacy & Security
      Certificates: View Certificates -> Servers: "Add Exception"
  • paste the URL of the website (https://xxx.xxx) in it's Location field.

Let Firefox retrieve the certificate -> "Get Certificate"

  • click the "View" button and inspect the certificate

You can see detail like the issuer of the certificate and intermediate certificates in the Details tab.

See also: