I've got the same error. Looking at file stdout.log from
Tomcat's logs directory, I've found that the following error occurs just before the subject:
java.lang.ArrayIndexOutOfBoundsException: 3
at net.jforum.ActionServletRequest.<init>(ActionServletRequest.java:256)
at net.jforum.JForum.service(JForum.java:203)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
... more lines belongs to Tomcat's code.
[originally posted on jforum.net by Anonymous]