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When I enter a company name into search this message appears:

Secure Connection Failed

An error occurred during a connection to vanilla-search.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.

Learn more…

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?

I am getting a message that secure connection failed, it is happening for Amazon.com and maybe netflix as I can't log on or access the sites

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

Secure Connection Failed

An error occurred during a connection to upl-upm.pushbuttonformula.com. SSL received a record that exceeded the maximum permissible length.

Error code: SSL_ERROR_RX_RECORD_TOO_LONG

I'm reposting a question already opened here because a moderator suggested to do so. Actually I though I was posting to the international forum from the URL...

I was trying to access a local HTTPS website of an embedded device (a Siemens S7-1500 PLC) that is using a self-signed certificate, but was unable to go on (attached image #1, in Italian language) due to the the SEC_ERROR_REUSED_ISSUER_AND_SERIAL error. I've browsed a similar PLC webserver in the past, so the fact that the device exposes a similar certificate serial number is not so strange for me, considering also it's self-signed.

The problem is that I cannot follow the instructions of the Mozilla knowledgebase here because I'm not able to identify the correct certificate of the website!

In the attached image #2 you can see that the connection is detected as not encrypted, I suppose because only the form part of the HTML that is posting the data using HTTPS while the rest is using HTTP, but I'm not sure. If I click on the padlock icon (attached image #3) the info about the current certificate is not displayed.

Then I went into Tools > Options and searched for "certificates"; as you can see in the attached images #4 and #5, neither in the Servers tab nor in the Authorities tab I can find any item that is related to 192.168.10.2 (the webserver IP address) or Siemens (the embedded device manufacturer). But unfortunately the error persist! Initially there was a 192.168.10.2:443 line in the Servers tab and I removed it and restarted Firefox, but it didn't solve, so at the moment the situation is the one depicted by the attachments.

I had to use Microsoft Edge to access the website, but I would like to solve this issue and use Firefox instead. Is there anything else I can do to bypass the error? Why doesn't the error page provide a way to correctly identify the wrong certificate using its fingerprint and/or name? Or, maybe, is there a way to disable this check for local IP addresses or for items in a whitelist?

Thanks for your help.

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.

need to be able to download my old sites. and stop getting error 522 can not connect to some sites due to not secure anymore... help need to watch some movie sites.. Jose

Be careful. Something doesn’t look right.

Firefox spotted a potentially serious security issue with www.aol.fr. Someone pretending to be the site could try to steal things like credit card info, passwords, or emails. ??????? I used Aol since 1998 !!!!!!!!

Your computer thinks it is May 1, 2026, which prevents Firefox from connecting securely. To visit www.olx.com.br, update your computer clock in your system settings to the current date, time, and time zone, and then refresh www.olx.com.br.

Why does my older computer running Windows 7 keep losing the ability to access "https:// sites"?

To resolve, I have to reset the network adapter (sometimes successful) or restart the computer to access these sites.

Firefox spotted a potentially serious security issue with westdell.fortiddns.com:40443. Someone pretending to be the site could try to steal things like credit card info, passwords, or emails. Advanced I can't open a lot of sites, I can click on advanced and select to open the site at risk but will not open. I can open these site in Google Chrome or Safari no problem. i follow the article "How to disable the Enterprise Roots preference" and turned both to "False" and still not luck Thanks

i was using facebook until about 4 weeks ago. somehow it changed languages and while i was trying to put it back to english i was locked out.

this is part of the message i get

Firefox detected a potential security threat and did not continue to www.facebook.com because this website requires a secure connection.

www.facebook.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.

The issue is most likely with the website, and there is nothing you can do to resolve it.

I am trying to access static IP addresses on my Intranet. I could in the past type in the IP address and I would get a notice that the site is not secure and allow me to continue to the site. Now it tells me that the website cannot be reached. I need to get to the GUI interface of cameras on my network. How do I get this to work?

I am trying to log on to Gordon Bernard Calendar Co once there I am informed that it is an insecure web site. I have been there many times. The GB web person says the prob. is on my end. My computer is old and I have always used version 7.

Joe

So I'm trying to access Greenfly but I'm getting this error message: SEC_ERROR_REVOKED_CERTIFICATE.

Please see attached image as all checks are good for the credentials. I've tried erasing cookies but no luck.

Any other options?

Firefox Nightly | 138.0a1 (2025-03-10) (aarch64) MacBook Pro | M2 2022 | Sequoia 15.3.1

Zachowaj ostrożność. Coś tu nie gra.

Firefox wykrył potencjalnie poważny problem bezpieczeństwa na witrynie ohttp-gateway-merino.services.mozilla.com. Ktoś podszywający się pod nią może próbować ukraść dane karty płatniczej, hasła, adresy e-mail lub coś innego.

Witryna „ohttp-gateway-merino.services.mozilla.com” określa poprzez HSTS (HTTP Strict Transport Security), że Firefox ma się z nią łączyć jedynie w sposób zabezpieczony. Dodanie wyjątku w celu odwiedzenia tej witryny jest niemożliwe.