Firefox Community Forum

I am writing to report a recurring technical issue that began appearing today across multiple devices.

When attempting to access Google websites (specifically Gmail and Google News) using the Firefox browser, users are being prompted to identify themselves via a security certificate. Previously, this authentication step did not occur, and access was seamless.

Key Observations:

Impact: We have confirmed this behavior on three firm-issued computers as well as one personal device.

Browser: The issue is isolated to Firefox; other browsers appear unaffected.

Timing: This behavior was not present yesterday; it started manifesting today.

We suspect this may be related to a recent network configuration change, a new security policy rollout, or a browser update that has altered how Firefox handles trusted connections to Google services.

Could you please inform me whether there have been any recent changes to our SSL inspection proxies, root certificate stores, or DNS configurations? Additionally, does anyone else on the team have visibility into a widespread incident affecting Google certificates, or should we proceed with troubleshooting individual profiles?

The SSL cert has been installed by the entity (Gridhost) from whom I have bought it for 20 years. And as explained, Firefox still shows it as Not Secure while Chrome say it is secure.

Hello,

Since this morning, I haven't been able to access Bsky on my laptop because of a supposed HSTS risk, which means I can't add an exception to visit it. I use Firefox on my Android and going to the mobile version of the website lets me in no problem, so I assume there's an issue with my laptop.

I'd usually wait a few days and let it solve itself but just in case it's something on my end, I'd like to solve it! I'm on 151.0.4 (64-bit), don't use a VPN or an anti-virus, I have a couple of privacy add-ons but they've been here forever and they've never caused a fuss. I can post a screenshot of the error code and the certificate it sends me if it's any help.

I'd appreciate any pointers! Thanks!

Hello, I noticed that when browsing webpages in Firefox, a window periodically appears asking me to confirm a certificate, presumably from a website (roughly called lt3.google). I haven't downloaded anything malicious and I regularly scan my system with an antivirus. Please help and respond. Thanks in advance.

Today I got the Firefox message "Secure Connection Failed" when I composed and tried to send Yahoo email to a friend who I have corresponded with for several years. In addition, a few months ago I could not connect on a Televisit with my doctor when I clicked the link her office sent. Again I got the Firefox message "Secure Connection Failed."

Hi.

Why i need every time i restart the firefox esr accept the cudy.net certificate? Look the picture.

Is there a way to add it as exclude this certificate and NOT ask me every time i restart the firefox esr to accept this certificate?

I am trying to access the FoodsCo website, a division of Kroger and I get a page saying that the "authenticity of the received data could not be verified."I cannot go the page at all (screenshot of what I get when I try to access foodsco.net). I checked the same page on Chrome and the page shows up fine and the connection is secure (the website literally has https in it. The S stands for secure). I have tried to add foodsco.net to the exempt list through Enhanced Tracking Protection, but it didn't work. This isn't some dark web site, it's connected to the biggest grocery chain the U.S. I'm very confused here. What is happening?

Since we had service to our router and modem, I have been receiving a notice "Secure Connection Failed" whenever I click on a link. It states that something is too long. What can I do to resolve this situation as some of the links are important. I would appreciate your help. Thanks!

Have used Firefox for years. Today, went to standard sites (eg weather info, local blog site) and get told they aren't secure and can't be loaded. Have tried re-installing Firefox, clearing cookies but no change. No problem with same sites from Chrome. Message is:

Looks like there’s a problem with this site

www.portlandbirdobs.com sent back an empty page. What can you do about it?

   The site could be temporarily unavailable or too busy. Try again in a few moments.
   If you are unable to load any pages, check your computer’s network connection.
   If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the web.

Error Code: NS_ERROR_NET_EMPTY_RESPONS

This is the message that pops up when I am in my yahoo.com email account. Does his have anything to do with Firefox? How do I get rid of it, looks suspicious.

Rich Randall

Secure Connection Failed

An error occurred during a connection to fen.peryuck.com. SSL received a record that exceeded the maximum permissible length.

Beginning today, I suddenly cannot access numerous websites when I use Mozilla Firefox 151.0.2. Examples include Amazon, and Google, et al. Attempts to do so consistently fail at the point of performing a TLS handshake, when I am advised that "secure connection failed". Kindly refer to the attached screenshots. I have no difficulty whatsoever accessing the same websites when I use other browsers, such as Google Chrome and MS Edge. I previously had Mozilla Firefox enabled as my default browser, but I have had to change this, given these "challenges". Please advise how I can fix this. Best regards and many thanks.

When following a link from a news website I keep getting this message - Secure Connection Failed - The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. It loads on my iPhone and other browsers using the same link. What setting do I need to address to get this to stop?

Current Setup: OS: Windows 11 Home (10.0.26200) Firefox Version: 151.0.2 (Build ID: 20260525130955)

Issue:

• Firefox suddenly is unable to connect to any wesbite
• All attempts to browse result in the "Secure Connection Failed" screen
• All other browsers function fine with no network connectivity issues

Exact Display Text:

Secure Connection Failed

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. What can you do about it?

The issue is most likely with the website, and there is nothing you can do to resolve it. You can notify the website’s administrator about the problem.

Attempted Fixes / Things Confirmed:

• Everything mentioned in: Firefox can't load websites but other browsers can

• Relevant about:config values:

* * security.enterprise_roots.enabled -> True

• * security.ssl.enable_ocsp_must_staple -> True
• * security.ssl.enable_ocsp_stapling -> True
• * security.tls.version.max -> 4
• * security.tls.version.min -> 3

• System locale and timezone are correct
• DNS over HTTPS is set to OFF
• HTTPS-Only Mode is set to Don't enable HTTPS-Only Mode
• Restarting in Troubleshooting Mode
• Disabling the Anti-Virus (including the device Firewall)
• Disabling any VPNs or network proxies
• Clearing cache and browsing history
• Clearing certificates from the Certificate Manager in Settings
• Attempting connection with a newly created profile
• Clearing the cert9.db file for Firefox to reset certificate information
• Refreshing Firefox (resetting it completely)
• Uninstalling and reinstalling Firefox (after clearing all Mozilla related %appdata% folders)

Observations

• When trying to mess with the device timezone and see if changing it back to the correct one would "reset" something, after a few attempts of starting Firefox in the wrong timezone and then restarting it after changing to the correct one, for a single session, I was able to browse normally again. I closed Firefox to see if the problem was fixed but it went back to the "Secure Connection Failed" page. Was unable to reproduce the same behavior.

• Tried installing a portable version of Firefox (151.0.3) from Firefox Portable .

After installation, the first session works perfectly fine but after I close the session and restart Firefox, it gives the same "Secure Connection Failed" message.

• * Reinstalling the portable version in the folder, gives the error from the get-go, not even the initial post-installation session works but installing in a different folder works fine for the first session but all subsequent restarts (sessions) of the browser give the same error.

I just installed Firefox on my PC haven't had it on this computer since reinstalling windows - I imported my bookmarks and passwords from Edge, thinking it would be a seamless transition, since I used Firefox in the past without much trouble.

Two weeks on, about 95% of every page I open gives an error similar to the one below, and I have to shift+refresh several times to get it to reload before it goes away, (some sites still don't open).

I wonder how common this issue is, and how people fixed it?

Be careful. Something doesn't look right.

Firefox spotted a potentially serious security issue with connect.mozilla.org. Someone pretending to be the site could try to steal things like credit card info, passwords, or emails.

Go back (Recommended)

Hide advanced

Advanced What makes the site look dangerous? The site is set up to allow only secure connections, but there's a problem with the site's certificate. It's possible that a bad actor is trying to impersonate the site. Sites use certificates issued by a certificate authority to prove they're really who they say they are. Firefox doesn't trust this site because its certificate isn't valid for connect.mozilla.org. The certificate is only valid for: *. eero.com. What can you do about it? Probably nothing, since it's likely there's a problem with the site itself. Sites use certificates issued by a certificate authority to prove they're really who they say they are. But if you're on a corporate network, your support team may have more info. If you're using antivirus software, try searching for potential conflicts or known issues. View the site's certificate Learn more about secure connection failures Error Code: SSL_ERROR_BAD_CERT_DOMAIN Jun 5, 2026 10:58:34 AM GMT+10

Proceed to connect.mozilla.org (Risky)

This message was received when I tried to follow the support link "support.mozilla.com".

Secure Connection Failed

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. What can you do about it?

The issue is most likely with the website, and there is nothing you can do to resolve it. You can notify the website’s administrator about the problem.

I cannot access any site on the internet, including all that I use normally like mail and newspaper sites, medical provider websites. Neither Firefox nor Safari work--I get the same error message on both. This doesn't happen with other isp providers, like a public computer in the library, just at home. Could there be a modem or isp provider problem at my home?