Firefox reports invalid Security Certificate but doesn't allow you to add an exception

By Selwyn Polit, Wed, 08/25/2021 - 08:05

My beloved Firefox has been doing something strange when it tries to view websites that have certificate problems such as expired certificates.  For some reason my desktop computer would pop up a bland dialog box whining about the site uses an invalid security certificate.  My laptop doesn't seemt to do this.  Apparently no-one on the internet has ever experienced this problem so I felt it would be useful to share the solution with folks. 

 

Here is the alert box:

Thanks to a lovely person who goes by cor-el on the mozilla support website, I got the following solution which I am translating so it will be comprehensible to mere mortals.  (For Techies: You should set the browser.xul.error_pages prefs to true on the about:config page.)

Essentially it involves the following steps:

  1. Type about:config into firefox where you would normally type a URL. (see screen shot)
  2. type browser.xul in the Search box
  3. double click on the line that says: browser.xul.error_pages.enabled and making certain that the Value is true. 

 

When Firefox is configured correctly (Don't ask me how it became unconfigured..) the dialog looks like this:

 

This peson also kindly offered a little more information about how to fiddle with the about:config options in firefox.  Be gentle - you can break some stuff.

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

And while we are here, you can find the stored certificates at Tools / options / advanced tab / view certificates / servers tab.

 

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