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Permalink to this page: https://cwiki.apache.org/confluence/x/tSklBg

Preface

This page discusses the various ways you see Class Not Found errors or very similar errors. It is strongly advised you read the following topics:

If you get a NoClassDefFoundError exception, the root cause might be the same as for a ClassNotFound exception.

Questions

  1. Why is jsp:useBean is not working?
  2. Why do I get java.lang.NoClassDefFoundError: javax/servlet/Filter?
  3. Why do I get java.lang.NoClassDefFoundError: org/xml/sax/InputSource?

Answers

Anchor
Q1
Q1

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Why is

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jsp:useBean

...

is not working?

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Make sure:

  • Your bean is packaged in a class.
  • You have fully qualified your class name (

    eg: No Format

    e.g.: com.bar.package.MyClass

    ) OR

  • You have imported your class into your jsp (

    eg: No Format <%@ page

    e.g.: <%@ page import="com.bar.package.MyClass"%>

     )

Anchor
Q2
Q2

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Why do I get

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java.lang.NoClassDefFoundError:

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javax/servlet/Filter

...

?

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You probably have servlet-api.jar floating around somewhere it shouldn't be. This really messes up the classloaders since Tomcat's classloaders don't act quite as normal as one expects (see links above). servlet-api.jar should only be found only once in $CATALINA_HOME/common/lib.

Anchor
Q3
Q3

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Why do I get

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java.lang.NoClassDefFoundError:

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org/xml/sax/InputSource

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?

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You have conflicting XML api jar files in your classpath. Read the README or RELEASE-NOTES for more information.

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