Cannot change version of the project facet Dynamic Web Module to 3.1.

The root cause of this problem is that the version of the web is also projcect with the inconsistent version of facet configuration!!

1. Modify the version of Project face

Here, we select 2.5, open the. settings\org.eclipse.wst.common.project.facet.core.xml file with Notepad, locate the "Installed facet=" Jst.web ", We'll change the value of version to 2.5.

2. Modify the version of Web. xml

Similarly, in order to ensure the consistency of the version, here also must be 2.5, we open web-inf\web.xml with Notepad, will "Web-app" node http://java.sun.com/xml/ns/javaee/web-app_#_#. The XSD is changed to http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd, and the value of version is changed to "2.5"

3, update maven

Right-click the project and then execute the right-click menu of Maven---Update project ... command to wait until the progress bar on the right bottom of eclipse disappears, and the MAVEN error message disappears.

Note: Here said 2.5 is not a random value, if you are using TOMCAT7 or lower version, then you can only use the version below 3.0, otherwise you are unable to add items to tomcat, even if the blind churn added, it is not normal to start Tomcat. In addition, fill in this version of the Http://java.sun.com/xml/ns/javaee/web-app_#_#.xsd file must be able to find the real, otherwise it is not possible, such as you write Http://java.sun.com/xml/ns /javaee/web-app_2_3.xsd, you can't actually find it.

Cannot change version of the project facet Dynamic Web Module to 3.1.