What do the security warning codes mean?

Revision Information
  • Revision id: 108775
  • Created:
  • Creator: dkeeler
  • Comment: initial content for "Your connection is not secure" page
  • Reviewed: Yes
  • Reviewed:
  • Reviewed by: heyjoni
  • Is approved? Yes
  • Is current revision? No
  • Ready for localization: Yes
  • Readied for localization:
  • Readied for localization by: heyjoni
Revision Source
Revision Content
Firefox versions 43 and lower: This article applies to newer versions of Firefox.

When Firefox connects to a website using HTTP over TLS (i.e. the URL begins with "https://"), it must verify that the certificate presented by the website is valid and that the encryption is strong enough to adequately protect your privacy. If the certificate cannot be validated or if the encryption is not strong enough, Firefox will stop the connection to the website and instead show an error page.

For certificate errors, Firefox will show a page with the following content: badssl-mismatch

For weak encryption, Firefox will show a page with the following content: badssl-rc4

If you encounter either of these pages, it is recommended that you wait for the website to be fixed before using it. Otherwise, any personal information you enter into the site may potentially be stolen. To bypass the error page and continue to use the site, click the "Advanced" button and follow the directions in the resulting dialog.