How to solve this java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream?

The particular exception message is telling you that the mentioned class is missing in the classpath. As the org.apache.commons.io package name hints, the mentioned class is part of the http://commons.apache.org/io project.

And indeed, Commons FileUpload has Commons IO as a dependency. You need to download and drop commons-io.jar in the /WEB-INF/lib as well.

See also:

• How to upload files to server using JSP/Servlet?
• How to add JAR libraries to WAR project without facing java.lang.ClassNotFoundException? Classpath vs Build Path vs /WEB-INF/lib
• How do I import the javax.servlet API in my Eclipse project?

use maven dependency

<dependency> 
  <groupId>org.apache.commons</groupId>
  <artifactId>commons-io</artifactId> 
  <version>1.3.2</version> 
</dependency> 

or download commons-io.1.3.2.jar to your lib folder

Solution

By default, Struts is using Apache “commons-io.jar” for its file upload process. To fix it, you have to include this library into your project dependency library folder.

1. Get Directly

Get “commons-io.jar” from official website – http://commons.apache.org/io/

2. Get From Maven

The prefer way is get the “commons-io.jar” from Maven repository

File : pom.xml

  <dependency>
    <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
    <version>1.4</version>
  </dependency>