Starting in version 11.6, some of the underlying page names have changed in the web application. Customers using bookmarks or shortcuts that point to the previous page names, rather than the top-level URL of the Enforce server, may see errors when opening these pages. Ensure that you are browsing directly to the root URL, e.g. https://enforceserver.yourcompany.com/
If the error persists even when browsing to the root, check the URL in the file: \Vontu\Protect\tomcat\webapps\ROOT\index.html (Windows) or /opt/Vontu/Protect/tomcat/webapps/ROOT/index.html (Linux). This file contains a meta tag that redirects to the Enforce web application, which sometimes is not updated during an upgrade, particularly if the file has been manually changed or customized after installation. You should confirm that this refers to the new location.
The old meta tag, prior to version 11.6, was:
<meta http-equiv="refresh" content="0; url=/ProtectManager/Navigate.do?menuID=default">
It should refer to the 11.6 version, which is:
<meta http-equiv="refresh" content="0; url=/ProtectManager/enforce/navigate?menuID=default">