Firefox Community Forum

To be honest. Firefox is starting to be a big pain to use. I'm starting to see more and more of this screen where it say's "Be careful. Something doesn't look right" Even when i go to the advance and say proceed. Nothing happens and i'm getting no where. I know many of the sites don't have anything to do with asking for credit card, Scam or even having popup's. I test the sites in other browsers and there work without any issues. But Firefox is starting to lock me out of many sites due to this. How can i make this stop. As i used Firefox for many years.

The sample that is in the screenshot is a Anime data base that i have also used for years. But today shows this. But was working fine yesteday. What is going on and how can i fix it. So i can start using the browser that i love on the sites i want to.

you are blocking "entry.ostralia.cc" saying the ssl is expired....

BUT SSLCHECKER link text shows it's OK ! and all other browsers allow it...

you could at least allow me to access it under the 'advanced' option like in earlier days...

( the Host provider has mixed up billing for the 3 SSLs on my site , but all 3 are active and valid SSLs...)

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!

Please help me purchase a NM Gift Certificate for my daughter Caroline Campbell. She has an account with you but I do not and I'm overwhelmed by the process. Lisa Nichol [edited email from community support forum]

I have started receiving a secure connection failed error message for a portal log-in website that worked fine for the past 6-7 months (see attached document). Other people in my group use Firefox and Bitdefender to access the portal and none of them are having this issue.

I originally believed the problem to be my anti-virus (Bitdefender) and worked with them to resolve the problems. After trying various solutions including clearing my cache, using private mode and turning off different components of their software, Bitdefender believes the problem is with my browser setting and not their software. I also tried accessing the portal using Chrome in both regular and incognito modes and cannot access the site which would seem to rule out the problem being a Firefox browser problem but contacting Firefox support seems to be the next logical step.

I have been to the Firefox FAQ and saw similar problems with potential solutions - DNS over HTTPS, TLSKEYLOGGING issues, add-on exceptions - none of which worked. I have the most recent version of Firefox and am running Windows 11 home version.

Sometimes if I hit refresh after receiving the error message, the browser will try to connect and I will get a server time out message. If I keep hitting "try again", sometimes the portal log-in screen will appear and allow me to log-in. The key word is "sometimes" since often I just keep getting the server time out message.

Any ideas for me to try from this forum?

I was going to look at a friend's website that has an SSL-certificate, has had it for years, which has been working all that time. Now Firefox informs me: "Firefox doesn’t trust this site because its certificate isn’t valid for www.wuwei-school.nl. The certificate is only valid for: wuwei-school.nl."

Really? I pretty sure there's nothing wrong with the certificate and I was taught that the "www" component is not important as a prefix for the domain name in a URL. It is just a shorthand code to show that the address is a URL. Can Mozilla fix this issue? Or, at least, explain?

Thanks

Firefox's full message: - - - Be careful. Something doesn’t look right.

Firefox spotted a potentially serious security issue with www.wuwei-school.nl. 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 www.wuwei-school.nl. The certificate is only valid for: wuwei-school.nl. 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

Aug 21, 2026 11:10:31 PM GMT+2 - - -

Доброго времени суток.

Я установил сертификаты по инструкции, которая лежит на s.sber.ru/70VQ2B . После этого не прогружается полностью окно входа на online.sberbank.ru (не видно содержимого фреймов). Проблема полностью аналогична описанной здесь: https://support.mozilla.org/ru/questions/1597415

Firefox ESR115.40 (64-разрядный, Windows 7) - страница выглядит, как на скриншоте по ссылке выше.

Установлены скачанные сертификаты в самом браузере, они отображаются в разделе Управление сертификатами -> Центры сертификации. После этого абсолютно ничего не изменилось.

Может, надо еще что-то сделать? Или на Firefox ESR115.40 вообще работать не будет? До перехода на сертификат от Минцифры России проблем не было.

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.

When I bring up the certificate-expired URL

<https://oaklandwiki.org/>

in Firefox 149.0 on Windows 11 I am told "You have added a security exception for this site." But not how to remove it. How do I do that? I did not see anything in Settings or about:config; did I miss it?

Hello, I am facing a very strange and frustrating issue with my website https://biografieblick.de/, and it is only happening on the firefox browser other browsers like chrome, edge or safari are loading the site perfectly fine. The Issue is it occurs occasionally, Yeahh IDK why. When I try to visit my site, Firefox gets stuck on a screen that says "Checking if the site connection is secure" and it looks like an loop sometimes.

This looks exactly like a cloudflare turnstile loop but I am NOT using cloudflare. I have double checked my DNS records and explicitly confirmed this with my web hosting provider. This block only triggers when using firefox.

I keep getting a messages anytime I try to visit a site which I have been to before? here's an example

"mail.aol.com 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."

Secure Connection Failed

The connection to www.tab.com.au was interrupted while the page was loading.

   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.

Hello, I run a movie and drama-related website: https://tvmon.com.co/. Recently, I’ve noticed that Firefox occasionally throws the following error when trying to access the site:

"Secure Connection Failed An error occurred during a connection to tvmon.com.co. . The OCSP response contains an invalid signing certificate. Error code: SEC_ERROR_OCSP_INVALID_SIGNING_CERT"

This issue is very strange because:

1. The site loads fine in Chrome, Edge, and Safari.

1. My SSL/TLS certificate is valid, up-to-date, and passes external tests (SSL Labs, etc.).

1. The error only appears occasionally in Firefox, refreshing sometimes fixes it, sometimes not.

1. Hosting and server logs show no issues at all.

I suspect this is related to Firefox’s stricter OCSP validation, but I’m not sure how to debug or resolve it. Since my site streams drama and movie content, this error is frustrating for users who rely on Firefox.

Has anyone else experienced this intermittent OCSP signing certificate error? Is there a known fix or workaround for Firefox-specific validation issues?

Clear Error code: PR_END_OF_FILE_ERROR This is only on Amazon.com. Secure Connection Failed

An error occurred during a connection to www.amazon.com. PR_END_OF_FILE_ERROR

Error code: PR_END_OF_FILE_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.

Learn more…

I've never had Secure Connection Failed warnings before, but now I am getting them often. I don't want to stop using Firefox, but it seems I can get to these sites via other browsers.