I'm getting the following error and I have no idea what it is, I'm new to servlets and tomcat server as well, so could you explain to me how do I identify errors such as the error below?. Any help is appreciated.

```
java.lang.IllegalArgumentException: Document base C: \Users\ agrosys\ workspace\.metadata\.plugins\ org.eclipse.wst.server.core\ tmp1\ wtpwebapps\ JqTree does not exist or is not a readable directory
    at org.apache.naming.resources.FileDirContext.setDocBase(FileDirContext.java: 136)
    at org.apache.catalina.core.StandardContext.resourcesStart(StandardContext.java: 5145)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java: 5330)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java: 150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java: 1575)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java: 1565)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

```