关于myecliplse经常弹出【An error has occurred. See error log for more details. java.lang.NullPointer】的解决方法

项目基于：spring Boot 2.0.1 RELEASE
由于我们的项目不需要web.xml，所以它是空的，为了不再提示黄线，我们加上了

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_1.xsd http://xmlns.jcp.org/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="schedule-console" version="3.1"/>

然鹅，第二天上班的时候打开项目，myecliplse疯狂的提示
An error has occurred. See error log for more details. java.lang.NullPointer
改个代码要弹出十次八次的那种
去翻了好多资料，
有清理缓存的 Myeclipse.exe -clean 对缓存进行清理
有删除文件的

https://scanneran.iteye.com/blog/2206388
https://blog.csdn.net/u011885027/article/details/72903136
https://blog.csdn.net/W_Batman/article/details/78943209
https://bbs.csdn.net/topics/390908904

挨个试了一下，发现都不好使，
后来发现是web.xml的问题，因为xmlns:web写重了，，，
更改前

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

更改后

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