Serve Static Resources from the Visualforce Domain

This critical update changes the way that your static resources, such as images, JavaScript, and CSS files, are served from Salesforce. To avoid broken references to static resources, make sure that you review our recommended best practices.

Prior to this release, some static resources, such as images and CSS files, were loaded from the Salesforce Domain. With this update, all static resources are loaded from the Visualforce Domain. Changing the origin domain can cause absolute references to static resources to break.

It’s a best practice to reference static resources by using the $Resource global variable and the URLFOR() function instead of static strings. For example:
  • <apex:includeScript value="{!$Resource.MyJavascriptFile}"/>
  • <apex:image url="{!URLFOR($Resource.TestZip, 'images/Bluehills.jpg')}" width="50" height="50"/>
These references are safe to use regardless of your organization’s settings.

We recommend that you test this update in a sandbox or Developer Edition organization to verify correct behavior of your pages before enabling it in your production organization.

To activate this critical update:
  1. From Setup, click Critical Updates.
  2. Click Activate for “Serve Static Resources from the Visualforce Domain.”