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.