报错
Description Resource Path Location Type Cannot change version of project facet Dynamic Web Module to 2.5. web-test line 1 Maven Java EE Configuration Problem One or more constraints have not been satisfied. web-test line 1 Maven Java EE Configuration Problem
解决方案
1、右击项目名，打开"Properties"搜索"Project facets"，将"Dynamic Web Module"改为3.0，“Java"改为1.8
2、打开项目目录下的”.settings"下的"org.eclipse.wst.common.project.facet.core.xml"文件，修改jst.web的"version"为3.0
3、打开项目"src\main\webapp\WEB-INF"下的"web.xml"文件，将"web-app"标签(一般是第二行)内的"version"改为3.0
<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">
注意中：
“xsi:schemaLocation"改为"http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd” “version"改为"3.0”
执行这三个步骤即可解决改错误
