Exception while upgrading from S 2.0.11 to 2.1.6

[ManiKanta G]

Hi,

Today I've upgraded my application from 2.0.11 to 2.1.6, and I've added only
the 5 basic libraries (commons-logging-1.0.4.jar, freemarker-2.3.13.jar,
ognl-2.6.11.jar, struts2-core-2.1.6.jar, xwork-2.1.2.jar) required for
S2.1.6 to be up and run.

I encountered the below exception... (i've given the root exception only)

.....more
Caused by: java.lang.ClassNotFoundException:
org.apache.commons.fileupload.FileUploadException
    at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1360)
    at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1206)
    at java.lang.ClassLoader.loadClassInternal(Unknown Source)
    ... 28 more


But when I placed the commons-fileupload.jar in the lib, it is working. But
I didnt see that this jsr is required any where. Am I missing some thing? or
I overlooked that some where it is mentioned?

I m using Tomcat 6.0.16


ManiKanta