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What is error code:sec_error_unknown_issuer? I am getting this from my bank's billpay printout for electronic bills.


I talked with the computer teck at the bank and she assures me that the problem is not at their end and suggest that I contact Firefox to see why they are blocking this site.

Additional System Details

This happened

A few times a week

This started when...

Four days ago

Installed Plug-ins

  • Adobe PDF Plug-In For Firefox and Netscape "9.4.1"
  • Default Plug-in
  • Shockwave Flash 10.1 r102
  • Adobe Shockwave for Director Netscape plug-in, version 11.0
  • GEPlugin
  • 4.0.50524.0
  • Google Updater pluginhttp://pack.google.com/
  • Reader Library Helper Plugin
  • Google Update
  • Next Generation Java Plug-in 1.6.0_17 for Mozilla browsers
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.


  • User Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv: Gecko/20090824 Firefox/3.5.3 ( .NET CLR 3.5.30729)

More Information

  • Top 10 Contributor
  • Moderator
10749 solutions 96724 answers

You can check who issued that certificate.

You can retrieve the certificate to check who issued the certificate.
You should always do that to see if that helps to identify the problem (missing intermediate certificate or something else).

  • Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

  • Click the "View..." button to inspect the certificate and check who is the issuer.

If you can't add an exception, but get a pop-up with the error message then you can check the pref browser.xul.error_pages.enabled on the about:config page and make sure that the value is set to the true (default).

See http://kb.mozillazine.org/about%3Aconfig