Java agent not running after the upgrade to 8.5.1FP4

I recently upgraded our Domino servers from 6.5.4 to 8.5.1FP4. After the upgrade, the java agent failed to execute and I found the below message in the server log:

11/24/2010 12:07:32 AM Agent Manager: Agent error: java.io.IOException: Server returned HTTP response code: 500 for URL: http://127.0.0.1:80/europe/monitoring/monitoring.nsf/monitoring?openagent&Profile=Global_France

11/24/2010 12:07:32 AM Agent Manager: Agent error: at java.lang.Throwable.(Throwable.java:67)

11/24/2010 12:07:32 AM Agent Manager: Agent error: at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:930)

11/24/2010 12:07:32 AM Agent Manager: Agent error: at HTTPCheck.NotesMain(HTTPCheck.java:50)

11/24/2010 12:07:32 AM Agent Manager: Agent error: at lotus.domino.AgentBase.runNotes(Unknown Source)

11/24/2010 12:07:32 AM Agent Manager: Agent error: at lotus.domino.NotesThread.run(Unknown Source)

11/24/2010 12:07:32 AM AMgr: Agent ‘HTTPLaunch.java’ in ‘europe\monitoring\monitoring.nsf’ completed execution

JRE version on the server is j2re1.4.2_13

I found lot of below message in log as well “Process D:\Lotus\Domino\ncompact.exe (10560/0x2940) has terminated abnormall”

Thanks in advance.

Ravi S Doddi