This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

My Firefox 15.0.1 cannot verify any SSL CA, it says:"Cound not verify this certificate for unknown reasons." when I view the certificate status.

  • 4 respostas
  • 2 have this problem
  • 8 views
  • Last reply by apoph1s

more options

I recently switched to Windows 8 (from 7) and installed Firefox 15.0.1. Whenever I try to access a http secure page I get a message that "This Connection is Untrusted". If I click the Add exception button and view the certificate status I get the following message every time: "Cound not verify this certificate for unknown reasons."

I checked these sites in other browsers and they work just fine. I also checked the certificates using this site: http://www.networking4all.com/en/support/tools/site+check/

I've alreary tried to run firefox in compatibility mode and when that didn't help I reinstalled it but nothing's changed. I'm using chrome for the time being but I hope it's not the only solution.

I recently switched to Windows 8 (from 7) and installed Firefox 15.0.1. Whenever I try to access a http secure page I get a message that "This Connection is Untrusted". If I click the Add exception button and view the certificate status I get the following message every time: "Cound not verify this certificate for unknown reasons." I checked these sites in other browsers and they work just fine. I also checked the certificates using this site: http://www.networking4all.com/en/support/tools/site+check/ I've alreary tried to run firefox in compatibility mode and when that didn't help I reinstalled it but nothing's changed. I'm using chrome for the time being but I hope it's not the only solution.

Chosen solution

Which security software (firewall, anti-virus) do you have?

Some firewalls monitor secure (https) connections and send their own certificate instead of the website's certificate.

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

  • Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

  • Click the "View..." button and inspect the certificate and check who is the issuer.

You can see more Details like intermediate certificates that are used in the Details pane.

Ler a resposta no contexto 👍 2

All Replies (4)

more options

Make sure SSL protocols are selected in firefox.

Go to Tools-->Options-->Advanced-->Encryption

Under protocols make sure both SSL and TLS are checked.

ErikaV modificouno o

more options

Thanks for the answer, but both SSL 3 and TLS 1 are checked.

more options

Chosen Solution

Which security software (firewall, anti-virus) do you have?

Some firewalls monitor secure (https) connections and send their own certificate instead of the website's certificate.

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

  • Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

  • Click the "View..." button and inspect the certificate and check who is the issuer.

You can see more Details like intermediate certificates that are used in the Details pane.

more options

Thanks cor-el, you were totally right. I don't know how I didn't noticed that the certificate issuer was ESET in all cases. I refined my google search with this and found the same issue and the solution which was also provided by you. (https://support.mozilla.org/en-US/questions/923516)

So I turned off the SSL protocol filtering in ESET and the problem disappeared.