The Content Engine Client software enables communication between the Application Engine and the Content Engine. Install the latest release or fix pack version of the Content Engine Client files on all Application Engine servers.
Depending on the Content Engine Client versions that you have installed, you might have more than one instance of the Content Engine Client version 4.0 installed. Additionally, the version 4.0 Content Engine Client installer supported installing multiple instance of the Content Engine Client on the same server. Uninstall all instances before upgrading to Content Engine Client version 5.0.0.