HTTP ERROR 503: can not access /. Reason Service Unavailable

Question

My code is in github

https://github.com/shiblybcc/blog-aggregator

I have just created a spring framework project. This is my web.xml file code

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    version="3.0">
    <display-name>Course Rating</display-name>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
        <welcome-file>default.html</welcome-file>
        <welcome-file>default.htm</welcome-file>
        <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>
</web-app>

After I run my jetty server this works perfect and show the content of index.jsp file. But if I add following code in the web.xml file

<servlet>
    <servlet-name>dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>dispatcher</servlet-name>
    <url-pattern>*.html</url-pattern>
    <url-pattern>*.htm</url-pattern>
    <url-pattern>*.json</url-pattern>
    <url-pattern>*.xml</url-pattern>
</servlet-mapping>

I get the error

HTTP ERROR: 503    
Problem accessing /. Reason:    
    Service Unavailable

I am following a tutorial and they are doing the same. I don't understand what is wrong with my code. Thanks in advance.

Answer 1

After whole day research I found the solution here Getting Error scanning file when running jetty 9 on java 8 using the maven jetty plugin

Also I updated jetty, maven and tomcat. My current pom.xml

<build>
    <plugins>
        <plugin>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-maven-plugin</artifactId>
            <dependencies>
                <dependency>
                    <groupId>org.ow2.asm</groupId>
                    <artifactId>asm</artifactId>
                    <version>5.0.3</version>
                </dependency>
                <dependency>
                    <groupId>org.ow2.asm</groupId>
                    <artifactId>asm-commons</artifactId>
                    <version>5.0.3</version>
                </dependency>
            </dependencies>
        </plugin>
        <plugin>
            <groupId>org.apache.tomcat.maven</groupId>
            <artifactId>tomcat7-maven-plugin</artifactId>
            <version>2.3</version>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.3</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
    </plugins>
</build>

After updating everything, it is working fine now.