MyEclipse deployment when an internal error occurred errors in several cases

An internal error occurred during: "Add Deployment" often occurs when the Myecplise project is deployed to the application. Java.lang.NullPointException error. It's so depressing.
The reason is generally because the project is imported from elsewhere, down from CVS and so on.
Reason one, the JDK version is inconsistent. The steps are as follows:
Right-click the project name →properties→java Build path→libraries→ check JRE System library[sun jdk 1.6.0_13]→edit→ Select Workspace default JRE (Sun JDK 1.6.0_13) "→finish
The above is based on your local JDK version

Cause two, also the problem is the most frequent place: the project under the. mymetadata file content is inconsistent with the original project. There may be a missing Context-root property setting in <project-module, or the Value property in <attribute may be incorrect. So you need to compare the configuration file of the original project. Or try setting a different value for value, each time you set a change, you need to restart MyEclipse. Value probably has webroot,webapp,&lt;prjroot&gt;. such as
Give a sample configuration:
<?xml version= "1.0" encoding= "UTF-8"?>
<project-module
Type= "WEB"
Name= "COA"
Id= "myeclipse.1291700036453"
j2ee-spec= "1.4"
context-root= "/coa"
Archive= "Crm.war" >
<attributes>
<attribute name= "Webrootdir" value= "&lt;prjroot&gt;"/>
</attributes>
</project-module>

MyEclipse deployment when an internal error occurred errors in several cases