When you got the problem, it say ClassNotFoundException, com.hp.ilo2.remcons.remcons.class, while accessing remote console of HP server that still use the Integrated Lights-Out 2 (ILO2). Remote console uses the option: Access the system KVM from a Java applet-based console requiring the availability of a JVM.
The problem as figure below:
It means that the problem is in the Java. at this time The new Java version will not work with ILO2.
My solution to solve this problem ClassNotFoundException by downgrading the Java to the older Java version, to version 7 (mine is Java version 7 update 45, build 1.7.0_45-b18).
You can download from Java website (java.com) and choose the old versions. (remove the new Java, and install the Java version 7).
After installing back the old version 7, the problem is gone, remote console using ILO2 is work properly.