You will have this issue when you are running multiple Spring webapplications in the same container.
java.lang.IllegalStateException: Web app root system property already set to different value: 'webapp.root' = [/tmp/jetty-0.0.0.0-8080-springdemo.war-_springdemo-any-/webapp] instead of [/tmp/jetty-0.0.0.0-8080-greeting.war-_greeting-any-/webapp] - Choose unique values for the 'webAppRootKey' context-param in your web.xml files!
In Spring the webAppRootKey has a default value, which in this case obviously is the same for both applications.
Solve this by specifying the contextparam in your web.xml:
<context-param> <param-name>webAppRootKey</param-name> <param-value>specify.a.value.here</param-value> </context-param>