java.lang.IllegalArgumentException: The servlets named [X] and [Y] are both mapped to the url-pattern [/*] which is not permitted

Question

I am using Tomcat 7 as a webserver for a vaadin project // Eclipse as an editor .. It used to work fine but yesterday when I tried to run the server I got this error .. I tried to delete the server and create a new one .. but it didn't work

Caused by: java.lang.IllegalArgumentException: The servlets named [com.example.teamonelibraryapp_.Teamonelibraryapp_UI$Servlet] and [ui.AppMain$Servlet] are both mapped to the url-pattern [/*] which is not permitted
    at org.apache.catalina.deploy.WebXml.addServletMapping(WebXml.java:293)
    at org.apache.catalina.startup.ContextConfig.processAnnotationWebServlet(ContextConfig.java:2428)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsStream(ContextConfig.java:2103)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2064)
    at org.apache.catalina.startup.ContextConfig.processAnnotationsFile(ContextConfig.java:2057)
    at org.apache.catalina.startup.ContextConfig.webConfig(ContextConfig.java:1304)
    at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:889)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:386)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:117)
    at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5416)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    ... 6 more

Answer 1

The most important part of that trace seems to be

 The servlets named [com.example.teamonelibraryapp_.Teamonelibraryapp_UI$Servlet] and 
 [ui.AppMain$Servlet] are both mapped to the url-pattern [/*] which is not permitted
    at org.apache.catalina.deploy.WebXml.addServletMapping(WebXml.java:293)

So most likely, mapping those servlets to different url will solve your problem.