java.lang.NullPointerException
        at org.netbeans.core.startup.layers.ArchiveURLMapper.getURL(ArchiveURLMapper.java:82)
        at org.openide.filesystems.URLMapper.findURL(URLMapper.java:136)
        at org.netbeans.modules.j2ee.deployment.impl.DeployOnSaveManager.startListening(DeployOnSaveManager.java:169)
        at org.netbeans.modules.j2ee.deployment.devmodules.api.Deployment.enableCompileOnSaveSupport(Deployment.java:279)
        at org.netbeans.modules.maven.j2ee.POHImpl.refreshAppServerAssignment(POHImpl.java:208)
        at org.netbeans.modules.maven.j2ee.POHImpl$1.run(POHImpl.java:105)
        at org.openide.util.Mutex.postRequest(Mutex.java:1251)
        at org.openide.util.Mutex.postReadRequest(Mutex.java:565)
        at org.netbeans.modules.maven.j2ee.POHImpl.hackModuleServerChange(POHImpl.java:103)
        at org.netbeans.modules.maven.j2ee.POHImpl$2.propertyChange(POHImpl.java:122)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:276)
        at org.netbeans.modules.maven.api.NbMavenProject.doFireReload(NbMavenProject.java:459)
        at org.netbeans.modules.maven.api.NbMavenProject.access$200(NbMavenProject.java:82)
        at org.netbeans.modules.maven.api.NbMavenProject$AccessorImpl.doFireReload(NbMavenProject.java:123)
        at org.netbeans.modules.maven.NbMavenProjectImpl.fireProjectReload(NbMavenProjectImpl.java:514)
        at org.netbeans.modules.maven.api.NbMavenProject.fireProjectReload(NbMavenProject.java:453)
        at org.netbeans.modules.maven.api.NbMavenProject.fireMavenProjectReload(NbMavenProject.java:472)
        at org.netbeans.modules.maven.api.NbMavenProject$1.run(NbMavenProject.java:211)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:577)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1030)