Eclipse web.xml Referenced File Error

Question

I imported a project in eclipse as maven project - I upgraded the web-app versions from 2.5 to 3.1 because it got imported as Dynamic web Module 3.1. Now I am getting the following error :

The errors below were detected when validating the file "web-app_3_1.xsd" via the file "web.xml". In most cases these errors can be detected by validating "web-app_3_1.xsd" directly. However it is possible that errors will only occur when web-app_3_1.xsd is validated in the context of web.xml.

s4s-elt-character: Non-whitespace characters are not allowed in schema elements other than xs:appinfo and xs:documentation. Saw 'var _U="undefined";'

Related Questions:

1. Question1
2. Question2

Above 2 questions on SO point to the same issue and the answers suggests that the namespace should be javaee, which is already the case:

<web-app version="3.1" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_1.xsd">

Answer 1

Try this in your web.xml, note that xmlns points to http://xmlns.jcp.org

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee 
         http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

Try removing the web module entry from org.eclipse.wst.common.project.facet.core.xml save the file, Go to 'Project Facets' and change it to Dynamic Web Module Version 3.1.

Example