java.lang.NoSuchMethodError: javax.servlet.http.Ht

Any idea why I'm getting this error at runtime ? I'm trying to deploy an AsyncServlet on Jetty.

java.lang.NoSuchMethodError: javax.servlet.http.HttpServletRequest.startAsync(Ljavax/servlet/ServletRequest;Ljavax/servlet/ServletResponse;)Ljavax/servlet/AsyncContext;
        at my.server.SlowServlet.doGet(SlowServlet.java:16)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:705)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:814)
        at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:547)
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:480)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:119)
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:520)
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:227)
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:941)
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:409)
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:186)
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:875)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:117)
        at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:250)
        at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:149)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:110)
        at org.eclipse.jetty.server.Server.handle(Server.java:345)
        at org.eclipse.jetty.server.HttpConnection.handleRequest(HttpConnection.java:441)
        at org.eclipse.jetty.server.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:919)
        at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:582)
        at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:218)
        at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:51)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:586)
        at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:44)
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:598)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:533)
        at java.lang.Thread.run(Thread.java:680)

I've the following Maven dependencies in my pom.xml

    <dependency>
        <groupId>org.eclipse.jetty</groupId>
        <artifactId>jetty-server</artifactId>
        <version>${jettyVersion}</version>
    </dependency>


    <dependency>
        <groupId>org.eclipse.jetty</groupId>
        <artifactId>jetty-servlet</artifactId>
        <version>${jettyVersion}</version>
    </dependency>

    <dependency>
        <groupId>org.eclipse.jetty</groupId>
        <artifactId>jetty-servlets</artifactId>
        <version>${jettyVersion}</version>
    </dependency>


    <dependency>
        <groupId>org.eclipse.jetty</groupId>
        <artifactId>jetty-webapp</artifactId>
        <version>${jettyVersion}</version>
    </dependency>

I'm guessing your server is using the wrong version of the Servlet spec. AsyncContext is only available since Servlet spec v 3.0. You probably have the right version in your development environment, but your server uses an outdated version of the api, hence the error at runtime.