Mixed Content: Trouble viewing or creating proofs

Mixed Content

Workfront Proof web pages are secured using the HTTPS protocol which prevents man-in-the-middle attacks and eavesdropping by encrypting the data you send through your browser. In order to improve performance certain parts of the application connects over the HTTP protocol. Which include:

  • Files uploads: if the HTTP Upload feature is enabled
  • Loading of proof content into the Workfront Proof Viewer

NOTE All your connections over HTTP in Workfront Proof are safe and secured using unique tokens.

If a page contains a combination of both secure (HTTPS) and unsecure (HTTP) content, then this page is considered as Mixed Content.

There are two types of Mixed Content:

  • Active content: which includes scripts, iframes, links (e.g. CSS stylesheets)
  • Passive/display content: which includes images, embedded audio / videos, 

Starting with Firefox version 23, the Mixed Content Blocking feature was added which means active mixed content pages are blocked by default. Passive content can be manually blocked as a preference. If you have these settings enabled in your browser you may experience problems when connecting to certain parts of the Workfront Proof application.

Given the wide impact this new feature will pose to Firefox users we hope that Mozilla will introduce a mixed content whitelist option to an upcoming Firefox release. Additionally we are actively investigating to find a permanent solution to this problem. For the time being, the only solution is as follows:

HTTP Upload

If you have the HTTP Upload feature enabled on your account, your New proof / New version pages will contain Mixed Content. If your browser has the Mixed Content Blocking enabled you may notice that when submitting your proof the page freezes and uploads are never completed. 

The shield icon (1) to the right of the URL indicates that mixed active content is blocked.

To disable blocking on this page:

  • Click the shield icon to open the alert pop-up
  • Open the menu (3) to the right of the "Keep Blocking" button
  • Choose the "Disable Protection on This Page" option (4)
  • Refresh the page
  • Proceed with your submission

NOTE This disables blocking of mixed active content on this particular page only and you will need to repeat these steps with each new submission.

Another more permanent option would be to disable the Active Content blocking from the browser's preferences, by setting the security.mixed_content.block_active_content preference to "false". Please see the steps below.

Workfront Proof Viewer - proof images don't load

UPDATE: On 15th April 2015 we've introduced a solution that loads all the proof tiles over HTTPS, so the issues described below should not be happening any more.

However, if you are still experiencing issues with viewing the proofs, please have a look at our basic troubleshooting steps and contact our Support team at if you need any assistance.

When you click the "Go to proof" button, the Workfront Proof Viewer opens over HTTPS and we load the proof content (i.e. tiled images) over HTTP. This creates mixed passive content in your browser.

Starting in Firefox 23, mixed active content is blocked by default, but passive content is still allowed. However, it may be blocked manually (or e.g. by one of your plugins or add-ons). This may result in an empty Workfront Proof Viewer when opening the proof links.

In this case you won't see any mixed content alerts in the URL bar (as in case of blocked active content), but you can view the errors in the browser's console:

Mixed passive content can be unblocked by changing your browser's preferences. To do this:

  • Open your configuration panel by typing about:config (1) in the URL bar
  • Confirm (2) that you understand the risk of changing preferences

  • type "mixed" in the search bar (3) to find the preferences
  • double-click on a particular preference to change its value to false to enable HTTP connections:
    • security.mixed_content.block_active_content (4) - is responsible for blocking active mixed content (i.e. HTTP Uploads)
    • security.mixed_content.block_display_content (5) - is responsible for blocking passive mixed content (i.e. proof tiles in the Workfront Proof Viewer)


  • Re-open your Workfront Proof Viewer page

NOTE There may be various reasons for the proofs not loading in the Workfront Proof Viewer. If you still cannot view your proofs despite performing the above steps, please contact us at - we'll be happy to assist.

This article last updated on 2017-09-15 16:57:41 UTC