In Linux, under Reports tab, I try to check the health details of all monitors. I get the following Java Exception: ErrorDispatcherValve[localhost]: Exception Processing ErrorPage[exceptionType=java.lang.Throwable, location=/jsp/ErrorPage.jsp] java.lang.ClassCastException: java.lang.NoClassDefFound

In Linux, under Reports tab, I try to check the health details of all monitors. I get the following Java Exception: ErrorDispatcherValve[localhost]: Exception Processing ErrorPage[exceptionType=java.lang.Throwable, location=/jsp/ErrorPage.jsp] java.lang.ClassCastException: java.lang.NoClassDefFound

Solution: The display variable is not properly set. Open the file <AppManagerHome>\ startApplicationManager.sh and comment the following lines:
 
                # if [ "$DISPLAY" = "" ]; then
                    AWT_HEADLESS=-Djava.awt.headless=true
                # fi