An internal error occurred during: "JBoss Tools Model Update". (NPE)

If i open a .xhtml file in the VPE and try to auto complete a <f: <h: <s: or any other tag i get the following nullpointer and no autocompletion works after that (except standard html and <ui

java.lang.NullPointerException
at org.jboss.tools.jst.web.kb.internal.KbProject.getStorageFile(KbProject.java:350)
at org.jboss.tools.jst.web.kb.internal.KbProject.load(KbProject.java:248)
at org.jboss.tools.jst.web.kb.internal.KbProject.resolveStorage(KbProject.java:219)
at org.jboss.tools.jst.web.kb.internal.KbProject.resolve(KbProject.java:229)
at org.jboss.tools.jst.web.kb.internal.KbProject.addKbProject(KbProject.java:156)
at org.jboss.tools.jst.web.kb.internal.scanner.ClassPathMonitor.validateProjectDependencies(ClassPathMonitor.java:121)
at org.jboss.tools.jst.web.kb.internal.KbProject.load(KbProject.java:246)
at org.jboss.tools.jst.web.kb.internal.KbProject.resolveStorage(KbProject.java:219)
at org.jboss.tools.jst.web.kb.internal.KbBuilder.build(KbBuilder.java:95)
at org.jboss.tools.jst.web.kb.KbProjectFactory$1KbBuilderEx.build(KbProjectFactory.java:89)
at org.jboss.tools.jst.web.kb.KbProjectFactory$1.run(KbProjectFactory.java:102)
at org.jboss.tools.common.model.XJob.runInWorkspace(XJob.java:158)
at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)