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Due to new, security-focused changes, version 23 of the Firefox web browser will not open some links contained within Desire2Learn.

EDIT: The newest versions of Chrome and Internet Explorer (IE) will not open the same links.

Update - 28 August 2013

This issue affects more than just Firefox. For updated, and more complete information, please see "Understanding mixed content".


Firefox 23 blocks mixed active content, that is, web pages that include both encrypted and non-encrypted sections. Mozilla made the change with Firefox 23 in an effort to protect users from thieves who use non-encrypted sections within otherwise encrypted web pages as a way of stealing information. For instance, credit card information entered into an apparently secure web page on a shopping site might be copied elsewhere by a non-encrypted section within the store's shopping cart page.

How Desire2Learn Is Affected

Desire2Learn, a secure, encrypted website, offers several ways of linking out to web pages on other sites. Some links to outside, non-encrypted websites fit Firefox 23's strict definition of mixed active content, so even though the links aren't malicious, Firefox blocks them.

Specifically, Firefox 23 blocks any link to an external web page where:

  1. the external web page isn't encrypted
  2. the link is set to open in the same frame or the whole window

What to Do

As a Course Instructor

Please review the materials within your course and check all your links to external web pages.

Links to non-encrypted web pages begin with "http://". Links to encrypted web pages begin with "https://". The "s" indicates the web page is secure.

For each non-encrypted (http) web link you find, make certain the link is set to open in a new window. Do not choose either the "Same Frame" or the "Whole Window" option for non-encrypted links.

As a Student

Instead of Firefox, you may try a different supported web browser; however, the latest versions of Chrome and Internet Explorer (IE) also block mixed active content. Only Safari does not yet do so.

If you continue to use Firefox 23, you may run across links your web browser refuses to open. When this happens, Firefox will not display an obvious message. Instead, Firefox quietly adds a small icon of a shield ( ) to the left end of the address bar. Click the shield icon to open a pop-up, and within the pop-up click the down arrow to reveal the option, "Disable Protection on This Page". You will need to click the "Disable Protection on This Page" option for every Desire2Learn course page that contains one or more blocked links.