Andrea Girardi - It's my blog!

It is possible that after an upgrade you may encounter this error on some of the more complex pages and root cause provided by tomcat console is :

Unable to compile class for JSP
The code of method _jspService(HttpServletRequest, HttpServletResponse) is exceeding the 65535 bytes limit

To solve the issue you need to locate the file [Tomcat_Home]/conf/web.xml and search the file for ‘JspServlet’. This should return an xml node of containing some values. You will need to add an additional the same as the below.

<init-param>
     <param-name>mappedfile</param-name>
     <param-value>false</param-value>
</init-param>

The resulting block of the web.xml file, once you have inserted the above, should look like the code below.

<servlet>
	<servlet-name>jsp</servlet-name>
	<servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
	<init-param>
	    <param-name>fork</param-name>
	    <param-value>false</param-value>
	</init-param>
	<init-param>
	    <param-name>xpoweredBy</param-name>
	    <param-value>false</param-value>
	</init-param>
	<init-param>
	     <param-name>mappedfile</param-name>
	     <param-value>false</param-value>
	</init-param>         
	<load-on-startup>3</load-on-startup>
</servlet>

Save the file and restart the Tomcat service.