The "Your connection is not secure" page generally has an "Advanced" button to get more technical information. That would provide more clues for us to assist. Meanwhile, please check these articles:

• What do the security warning codes mean?
• How to troubleshoot security error codes on secure websites - the most commonly seen code after you click the Advanced button

Does that help, or can you give us a little more info?

I'm trying to go to Microsoft Update Catalog site to download updates for Windows 10 but keep getting the error below and can't connect?? I've done this a bunch of times and this is the first time I've ever seen this? Any help?

"Your connection is not secure

The website tried to negotiate an inadequate level of security.

catalog.update.microsoft.com uses security technology that is outdated and vulnerable to attack. An attacker could easily reveal information which you thought to be safe. The website administrator will need to fix the server first before you can visit the site.

Error code: NS_ERROR_NET_INADEQUATE_SECURITY"

Hi Lone_Gunman45, I do not get an error with this URL:

https://www.catalog.update.microsoft.com/Home.aspx

Does that work for you?

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Who is the the issuer of the certificate?

Could you please 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.

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