That is really strange. Is Google the only site that is affected?

Are you using a public internet access point? If so, try going to an insecure address like http://example.com/ to see whether the hotspot is somehow linked to Facebook and you need to sign in to use the internet. I'm not sure I would trust that, actually.

jscher2000 said

That is really strange. Is Google the only site that is affected? Are you using a public internet access point? If so, try going to an insecure address like http://example.com/ to see whether the hotspot is somehow linked to Facebook and you need to sign in to use the internet. I'm not sure I would trust that, actually.

No, this is the router in my home. I'm in the UK, so there's no funny content blocking or anything on the ISP side either.

And yes, Google is the only site affected. I've been forced to use bing whenever it happens (the problem is intermittent).

Does it mention the issuer of the certificate?

Can you provide more detail 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.

I hate to sound like an old episode of The IT Crowd, but have you tried turning the router off and on again?

cor-el said

[snip] SEC_ERROR_UNKNOWN_ISSUER

I'll have to wait until it happens again (it's working now), but to be clear, this problem does not produce a SEC_ERROR_UNKNOWN_ISSUER message.

jscher2000 said

I hate to sound like an old episode of The IT Crowd, but have you tried turning the router off and on again?

Many times, yes

Hi I do not think you mentioned the name of your A/V program or Firewall : 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

Please let us know if this solved your issue or if need further assistance.

Pkshadow said

Hi I do not think you mentioned the name of your A/V program or Firewall : 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

Please let us know if this solved your issue or if need further assistance.

Thanks for your response — I use Bitdefender, but, as I said in the original post, SSL scanning is off, so this shouldn't be an issue.

Furthermore, it's only google.com where this issue occurs, and I strongly doubt it'd throw up errors for Facebook if it was my antivirus.

You can do a malware scan just to be sure.

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware

cor-el said

Does it mention the issuer of the certificate? Can you provide more detail 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.

This error went away for a while, but it's back now. I haven't changed anything, either. Quick note: I cannot do the add exception thing as Firefox says it cannot connect. Later on, when I tried to do it again, it said that it provided a valid certificate and google worked again.

I can, at least, paste the certificate details from when the error showed up as directed in the above post, however. If anyone can make sense of the below, I'd appreciate it!:

https://www.google.com/search?q=bitdefender+vpn+security+agreement&ie=utf-8&oe=utf-8&client=firefox-b-ab

Unable to communicate securely with peer: requested domain name does not match the server's certificate.

HTTP Strict Transport Security: true HTTP Public Key Pinning: true

Certificate chain:

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Facebook cert again. How is that happening?

Can you connect in a private window? That should bypass page and DNS caches used in normal windows. However most add-ons still run in private windows and proxy settings would still apply.

Speaking of which, you can check that here:

• Windows: "3-bar" menu button (or Tools menu) > Options
• Mac: "3-bar" menu button (or Firefox menu) > Preferences
• Linux: "3-bar" menu button (or Edit menu) > Preferences
• Any system: type or paste about:preferences into the address bar and press Enter/Return to load it

In the search box at the top of the page, type proxy and Firefox should filter to the "Settings" button, which you can click.

The default of "Use system proxy settings" piggybacks on your Windows/IE "LAN" setting. "Auto-detect" can lead to a flaky connection. You may want to try "No proxy".

Any difference?

Try to rename/remove cert9.db and cert8.db in the Firefox profile folder with Firefox closed.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox