Every time I try to open any webpage I am suddenly getting a message: "the owner of www......com has configured their website improperly" & nothing will open.
I've been using Firefox all day then suddenly this afternoon it won't open any web page (not even https://support.mozilla.org). I get the same message each time: "support.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". Using Windows 7, Avast antivirus and AdGuard AdBlocker (standalone).
All Replies (3)
What's your computer system and Firefox version?
There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connections and send their own certificate.
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
http://kb.mozillazine.org/Error_loading_websites
- 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
Thanks for the advice. I've opened it today and it's working fine, so not sure what caused the problem.
Might be the problem was fixed. Wait a few days. If the problem is gone,
Please flag your last post as Solved Problem so others will know.