我有一台新的笔记本电脑，我想在RapidClipse项目中再次工作。因此，我安装了RapidClipse，打开了我的项目，并在Designer上遇到了Internal Server Error。我用谷歌搜索，找不到任何解决方案。这是错误代码：
Type Exception Report
Message com.vaadin.server.ServiceException: java.lang.IllegalStateException: Push is not available. See previous log messages for more information.
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
javax.servlet.ServletException: com.vaadin.server.ServiceException: java.lang.IllegalStateException: Push is not available. See previous log messages for more information.
com.vaadin.server.VaadinServlet.service(VaadinServlet.java:382)
com.xdev.communication.XdevServlet.service(XdevServlet.java:207)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.catalina.filters.AddDefaultCharsetFilter.doFilter(AddDefaultCharsetFilter.java:88)
org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
Root Cause
com.vaadin.server.ServiceException: java.lang.IllegalStateException: Push is not available. See previous log messages for more information.
com.vaadin.server.VaadinService.handleExceptionDuringRequest(VaadinService.java:1487)
com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1447)
com.vaadin.server.VaadinServlet.service(VaadinServlet.java:380)
com.xdev.communication.XdevServlet.service(XdevServlet.java:207)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.catalina.filters.AddDefaultCharsetFilter.doFilter(AddDefaultCharsetFilter.java:88)
org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
Root Cause
java.lang.IllegalStateException: Push is not available. See previous log messages for more information.
com.vaadin.ui.PushConfigurationImpl.setPushMode(PushConfiguration.java:207)
com.vaadin.server.communication.UIInitHandler.getBrowserDetailsUI(UIInitHandler.java:210)
com.vaadin.server.communication.UIInitHandler.synchronizedHandleRequest(UIInitHandler.java:74)
com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:41)
com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1435)
com.vaadin.server.VaadinServlet.service(VaadinServlet.java:380)
com.xdev.communication.XdevServlet.service(XdevServlet.java:207)
javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
org.apache.catalina.filters.AddDefaultCharsetFilter.doFilter(AddDefaultCharsetFilter.java:88)
org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
Note The full stack trace of the root cause is available in the server logs.
