Why do I get the error message "Loading your JavaScript Extension failed" in the Campaign Builder?

Summary:

Some users may report that they’re seeing the error “Loading your JavaScript Extension failed” when they open the Campaign Builder.

Reason:

If we look deeper -> Right click → inspect → then find → Object → Drop down arrow → this shows the full error “Access violation by field ProfileId in the object user”. If we check the Tab Rules, we then find a Tab Rule that contains the ProfileId and some users don’t have permission to it.

Important: “Loading your Javascript Extension failed” is not completely related, the key here is the permissions error in the browser console, once something fails on load it can start breaking other parts of the logic.

Open

Open

Solution:

The permission missing here is "View Setup and Configuration” in System Permissions.