Firefox browser has stopped opening websites on my Dell laptop. Get "secure connection failed" error message. Other browsers work just fine. I have refreshed, uninstalled and reinstalled Firefox from both firefox website (using Brave browser) and from MSN store.

Illustration of a fox looking at an orange warning sign. Be careful. Something doesn’t look right.

Firefox spotted a potentially serious security issue with hrms.devrising.in. Someone pretending to be the site could try to steal things like credit card info, passwords, or emails. 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 hrms.devrising.in. The certificate is only valid for: isp.afd2.jiohs.net, signup.jiohs.net, frontend.afd2.jiohs.net, www.frontend.afd2.jiohs.net, acc.afd2.jiohs.net, blk.jiohs.net.

After updating Firefox to a newer version, some websites that previously worked on the older version started displaying **"Page Not Secure"** and **"Page Expired"** errors, preventing them from loading correctly.

When I try to log in Hollywoodbets.net the page doesn’t want to open it says it is protected by WE1 certification so how I change that

Using firefox 140.6.0esr on Windows 10 with noScript and uBlock Origin

Infrastructure for my health insurance provider website uses a self-signed certificate. The infra has a different URL from the main page and was initially failing with "CORS failed", which turned out to be the cert issue.

I copied the infra URL from the dev tools network log and opened it directly, and accepted the invalid cert. I can see the new exception in cert_override.txt.

Then, after unblocking the site in uBlock origin, POST and GET requests to the infra URL succeed, but OPTIONS requests are still failing with "CORS failed", and security status "SEC_ERROR_UNKNOWN_ISSUER"

Is there anything else I can do so the OPTIONS request honors the exception in cert_override.txt?

How do you deal with this. Every time I open mail on Yahoo now after Win 10 and Monzilla updates this shows up. Secure Connection Failed

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

Error code: SSL_ERROR_RX_RECORD_TOO_LONG

   The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
   Please contact the website owners to inform them of this problem.

Thanks

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

I wish to add an exception to an address which I host locally. I've explored many options which didn't work such as: Adding HTTPS-Only Exception Disabling certain security features

Just updated Firefox desktop (Win 10 with ESU) to 140.10.0ESR and now every site I try to access gives

Secure Connection Failed An error occurred during a connection to www.google.com. PR_CONNECT_RESET_ERROR Error code: PR_CONNECT_RESET_ERROR The page you are trying to view cannot be shown because the authenticity of the received data could not be verified. Please contact the website owners to inform them of this problem.

Sites were all working fine literally right before. No other changes at all. Have restarted a few times. Have disabled antivirus and adblocker extensions. Same problem including at google.com and even firefox. Note on the About Mozilla Firefox window says " Failed to check for updates". Also cannot even use the links there to go to What's new or Firefox help etc. (Gives Secure Connection Failed error). No proxy server. Have tried turning anti virus completely off. Just a combined modem/router -- basically vanilla.

Firefox is my primary browser so this is extremely disruptive. I am using Edge to access sites and post this.. though curiously enough I noticed it gave some error when checking for updates. Do not want to do anything there or will lose complete access.

Any suggestions .. or how to go back to a previous version, if necessary. Need a workable connection to file taxes next week so this is important. Thank you.

Moderator note: This question has been edited to correct the formatting.

Whenever I try to connect to this sight I get PR_END_OF_FILE error. I am using windows 11. I have looked at numerous suggestions on how to resolve this without success. I am reluctant to create a new profile since I use Firefox on numerous computers.

I can't open netflix or https://predatorhunteroutdoors.com . Why am I 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. 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.

Whenever i try to connect to any site, it fails to load and displays the following error message:

This web site requires a secure connection. - The page you are trying to view cannot be shown because this web site requires a secure connection. - The issue is most likely with the web site, and there is nothing you can do to resolve it. - You can notify the web site’s administrator about the problem.

When i press 'advanced' it says: [Site name] has a security policy called HTTP Strict Transport Security (HSTS), which means that Firefox can only connect to it securely. You can’t add an exception to visit this site.

This happens on every site i try to visit. I am on a samsung phone running android version 15. Other browsers do not have this problem (i am sending this from opera), and firefox works fine on my other devices.

I just got a Netgear router. Firefox won't let me connect because of the self-certification. I can only get on the internet via my Proton VPN. How can I fix this?

Specifically, I get this message--The certificate is not trusted because it is self-signed.

I have a local Rocky Linux server running a nginx web server. I am using a Macos laptop. I am trying to install a self signed ssl certificate using openssl on my web server.. The certificate I generated works with Safari but not with Firefox. I have copied the certificate to both Safari and Firefox for local use. Privacy and Security, Manage Certificates, Your Certificates. Firefox complains that that my TLS is tls 1.1, when I am using tls 1.3:

An error occured during connection to tls-v1-1.badssl.com:1011. Peer using unsupported version of security protocol.

My test on my server shows:

sudo curl -v https://caprock.home

Connected to caprock.home (192.168.2.44) port 443 (#0)

• ALPN, offering h2
• ALPN, offering http/1.1
• CAfile: /etc/pki/tls/certs/ca-bundle.crt
• TLSv1.0 (OUT), TLS header, Certificate Status (22):
• TLSv1.3 (OUT), TLS handshake, Client hello (1):
• TLSv1.2 (IN), TLS header, Certificate Status (22):
• TLSv1.3 (IN), TLS handshake, Server hello (2):
• TLSv1.2 (IN), TLS header, Finished (20):
• TLSv1.3 (IN), TLS change cipher, Change cipher spec (1):
• TLSv1.2 (IN), TLS header, Unknown (23):
• TLSv1.3 (IN), TLS handshake, Encrypted Extensions (8):
• TLSv1.2 (IN), TLS header, Unknown (23):
• TLSv1.3 (IN), TLS handshake, Certificate (11):
• TLSv1.2 (IN), TLS header, Unknown (23):
• TLSv1.3 (IN), TLS handshake, CERT verify (15):
• TLSv1.2 (IN), TLS header, Unknown (23):
• TLSv1.3 (IN), TLS handshake, Finished (20):
• TLSv1.2 (OUT), TLS header, Finished (20):
• TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
• TLSv1.2 (OUT), TLS header, Unknown (23):
• TLSv1.3 (OUT), TLS handshake, Finished (20):
• SSL connection using TLSv1.3 / TLS_AES_256_GCM_SHA384
• ALPN, server accepted to use http/1.1
• Server certificate:
• subject: C=US; ST=Colorado; O=Caprock Development; OU=Caprock Development Home Base; CN=caprock.home; emailAddress=mike@white-home.com
• start date: Aug 12 19:26:04 2025 GMT
• expire date: Nov 13 19:26:04 2032 GMT
• common name: caprock.home (matched)
• issuer: C=US; ST=Colorado; L=Canon City; O=Caprock Development; OU=Caprock Development Home Base; CN=caprock.home; emailAddress=mike@white-home.com
• SSL certificate verify ok.
• TLSv1.2 (OUT), TLS header, Unknown (23):

> GET / HTTP/1.1 > Host: caprock.home > User-Agent: curl/7.76.1 > Accept: */* >

• TLSv1.2 (IN), TLS header, Unknown (23):
• TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
• TLSv1.2 (IN), TLS header, Unknown (23):
• TLSv1.3 (IN), TLS handshake, Newsession Ticket (4):
• old SSL session ID is stale, removing
• TLSv1.2 (IN), TLS header, Unknown (23):
• Mark bundle as not supporting multiuse

< HTTP/1.1 200 OK < Server: nginx/1.20.1 < Date: Tue, 28 Apr 2026 13:17:26 GMT < Content-Type: text/html; charset=UTF-8 < Transfer-Encoding: chunked < Connection: keep-alive < X-Powered-By: PHP/8.3.30 <

Caprock.home

• Connection #0 to host caprock.home left intact

Furthermore I can't seem to delete the certificate from Firefox and re add it?

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?

I have been using the G-MAIL account for a very long time. I have never experienced problems while using it. I have also on a previous occasion registered here at Firefox and used it successfully, the same g-mail account for my emails. I have just registered and I am now blocked from accessing my emails because of a false certificate. When I registered previously here on Firefox I was able to use the same g-mail account. When did its certificate become faulty?' How do I access my emails? Does this mean I have to start new email addresses acceptable here at Firefox or its a go back to where you came from or try somewhere else?