"webxml attribute is required" error in Maven

It would be helpful if you can provide a code snippet of your maven-war-plugin. Looks like the web.xml is at right place, still you can try and give the location explicitly

<plugin>            
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-war-plugin</artifactId>
  <configuration>
    <webXml>src\main\webapp\WEB-INF\web.xml</webXml>        
  </configuration>
</plugin>

<plugin>
    <artifactId>maven-war-plugin</artifactId>
    <version>2.4</version>
    <configuration>
        <failOnMissingWebXml>false</failOnMissingWebXml>
    </configuration>
</plugin>

This solution works for me (I was using 2.2 before). Also, I am using Java Based Configuration for Servlet 3.0 and no need to have web.xml file.

It works perfectly for me too.

<project>

.....

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <configuration>
                    <webXml>WebContent\WEB-INF\web.xml</webXml>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

This is because you have not included web.xml in your web project and trying to build war using maven. To resolve this error, you need to set the failOnMissingWebXml to false in pom.xml file.

For example:

<properties>
    <failOnMissingWebXml>false</failOnMissingWebXml>   
</properties>

Please see the blog for more details: https://ankurjain26.blogspot.in/2017/05/error-assembling-war-webxml-attribute.html

If you are migrating from XML-based to Java-based configuration and you have removed the need for web.xml by implementing WebApplicationInitializer, simply remove the requirement for the web.xml file to be present.

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