解决Cannot change version of project facet Dynamic Web Module to 3.1

Open web.xml from project structure http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> Servlet 3.0 Web Application

and update web.xml file for example change version = "2.5"

Also change the org.eclipse.wst.common.project.facet.core.xml file from your project .settings file Follow the steps

　　 1. Window > Show View > Other > General > Navigator

2. There is a .settings folder under your project directory

3. Change the dynamic web module version in this line to 2.5 4.Change the Java version in this line to 1.5 or higher

Now refresh your project and get set to run on your server.

Do follow the blog for the solution http://scrapillars.blogspot.in/2014/02/how-to-change-project-facet-in-eclipse.html

The solution is produced with image illustrations