AWS Lambda NoClassDefFoundError

Use the maven-shade plugin so that the JAR contains the dependencies in an uber-jar.

So, add this to your pom.xml

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>2.3</version>
        <configuration>
          <createDependencyReducedPom>false</createDependencyReducedPom>
        </configuration>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

Source: http://docs.aws.amazon.com/lambda/latest/dg/java-create-jar-pkg-maven-no-ide.html

Potentially you may have this issue https://github.com/aws/aws-lambda-java-libs/issues/2 which requires a downgrade to aws-lambda-java-events-1.0.0.jar

=== If this issue exists even after including shaded jar ===

If you have this issue even after having shaded jar then the issue should be related to aws-lambda-java-events package version (should be some incompatibility between AWS lamda version and newer aws-lambda-java-events version) . i.e. I had this issue with latest version (2.0.2) of aws-lambda-java-events package and I have to downgrade the version to 1.3.0.

Seems like newer aws-lambda-java-events version doesn't have many dependencies.

Sometimes you have to upload your lambda again. Also I got the same issue I fixed with this pom.xml:

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

   <dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>com.amazonaws</groupId>
      <artifactId>aws-java-sdk-bom</artifactId>
      <version>1.11.83</version>
      <type>pom</type>
      <scope>import</scope>
    </dependency>
  </dependencies>

 </dependencyManagement>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

   <build>
<plugins>
  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>2.3</version>
    <configuration>
      <createDependencyReducedPom>false</createDependencyReducedPom>
    </configuration>
    <executions>
      <execution>
        <phase>package</phase>
        <goals>
          <goal>shade</goal>
        </goals>
      </execution>
    </executions>
  </plugin>
</plugins>
 </build>
</project>