Maven package a web application and hits the following error message :

$ mvn package
//...
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-war-plugin:2.2:war 
(default-war) on project spring4-mvc-maven-ajax-example: 
Error assembling WAR: webxml attribute is required 
(or pre-existing WEB-INF/web.xml if executing in update mode) -> [Help 1]

Solution

1. For servlet container < 3, make sure WEB-INF/web.xml file exists.

2. For servlet container >=3, and NO web.xml web application, declares the following maven-war-plugin plugin, and set the failOnMissingWebXml option to false.

  <build>
	<plugins>
		<plugin>
			<groupId>org.apache.maven.plugins</groupId>
			<artifactId>maven-war-plugin</artifactId>
			<version>2.6</version>
			<configuration>
				<failOnMissingWebXml>false</failOnMissingWebXml>
			</configuration>
		</plugin>
	</plugins>
  </build>	

References

1. Apache Maven WAR Plugin
2. Apache Tomcat – Which version do I want?