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Vaadin Forum3. Vaadin 6, 7, 8Framework UI

Error using a FileDownloader in a popup window.

Tullio Bettinazzi
6 years ago Sep 01, 2016 11:27am

I try to use a FIleDownloader extension on a button in a popup window.
When I try to use it I get an error :
java.lang.NullPointerException
    at com.vaadin.server.FileDownloader.handleConnectorRequest(FileDownloader.java:134)
    at axioma.web.template.ui.components.DocumentDownloader.handleConnectorRequest(DocumentDownloader.java:24)
    at com.vaadin.server.ConnectorResourceHandler.handleRequest(ConnectorResourceHandler.java:90)
    at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1409)
    at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:364)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

Going deeper I saw the proble comse out because the handleConnectorRequest tryes to get the session using a getSession method which returns null.
The method returns null because it tries to get the UI, using getUI, which returns null.
How van I solve thate issue ?
Is it a bug ?
Tks
Tullio