It seems that this is caused by an inconsistency in the applet properties file. To resolve this issue, the following file will need to be modified: IBM\FileNet\WebClient\WorkplaceXT\WEB-INF\appletParameters.properties. For each instance of javaapi.jar on any entry in this file, add a corresponding entry for Jace.jar. For example you may see the following: # PE Applets Default jar/versions pe/trusted=pe, pe3pt, psclient, javaapi, wcm, peResources pe/archive=wcm.jar, wcmResources.jar, pe.jar, psclient.jar, psResources.jar, peResources.jar, pe3pt.jar, javaapi.jar, p8cjares.jar Append to the following: # PE Applets Default jar/versions pe/trusted=pe, pe3pt, psclient, javaapi, Jace, wcm, peResources pe/archive=wcm.jar, wcmResources.jar, pe.jar, psclient.jar, psResources.jar, peResources.jar, pe3pt.jar, javaapi.jar, Jace.jar, p8cjares.jar Once appletParameters.properties has been modified, rebuild the EAR file using the tools in the IBM\FileNet\WebClient\deploy directory. After rebuilding the ear file, redeploy the application to the Application Server. After successfully redeploying the ear file the Java applets should now open successfully using WPXT. Note: modified appletParameters.propertie file is also placed in the same folder.