When attempting to use the Difference Tool to compare changes on the Change History Details page when clicking on the Old or New Value in Audit and Control Management Server 2013:
you may receive the following error:
The content type text/html of the response message does not match the content type of the binding (text/xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly.
To fix the error, log into the ACM web server, go to Server Manager > Manage > Add Roles and Features, and in the Features list, enable HTTP Activation in .Net Framework 4.5 Features > WCF Services:
Perform an iisreset. The difference tool will then compare the values successfully: