Windows 10 reached EOS (end of support) on October 14, 2025. If you are on Windows 10, see this article.

Rechercher dans l’assistance

Évitez les escroqueries à l’assistance. Nous ne vous demanderons jamais d’appeler ou d’envoyer un SMS à un numéro de téléphone ou de partager des informations personnelles. Veuillez signaler toute activité suspecte en utilisant l’option « Signaler un abus ».

En savoir plus
Résolu Archivé

Certificate errors prevent me from accessing safe sites

MadScientist8

I am unable to access my gmail account or my Linkedin account with FireFox. I get a certificate error SEC_ERROR_UNKNOWN_ISSUER yet this is a valid site and account. When Firefox gives the error it will not allow me to add a certificate exception, so I cannot use Firefox for these sites and probably others.

I am unable to access my gmail account or my Linkedin account with FireFox. I get a certificate error SEC_ERROR_UNKNOWN_ISSUER yet this is a valid site and account. When Firefox gives the error it will not allow me to add a certificate exception, so I cannot use Firefox for these sites and probably others.

Toutes les réponses (3)

Solution choisie

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

Websites don't load - troubleshoot and fix error messages

http://kb.mozillazine.org/Error_loading_websites


  • MOZILLA_PKIX_ERROR_MITM_DETECTED
  • uses an invalid security certificate SSL_ERROR_BAD_CERT_DOMAIN
  • configured their website improperly

How to troubleshoot the error code "SEC_ERROR_UNKNOWN_ISSUER" on secure websites https://support.mozilla.org/en-US/kb/troubleshoot-SEC_ERROR_UNKNOWN_ISSUER

All I can say is Thank you

Glad to help. Safe Surfing.