How to generate PDF in Mendix. Getting below errors. Please guide how to resolve it.

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Getting below errors in microflow.   stack trace: An error has occurred while handling the request. [User 'demo_user' with session id 'ac79c314-XXXX-XXXX-XXXX-XXXXXXXXb090' and roles 'User'] -------- com.mendix.modules.microflowengine.MicroflowException: File document for microflow variable 'downloadpdf' should not be empty when calling download file.     at MyFirstModule.PDF_Generation (DownloadFile : 'Download file downloadpdf') Advanced stacktrace:     at com.mendix.modules.microflowengine.MicroflowUtil.processException(MicroflowUtil.java:85) Caused by: java.lang.IllegalArgumentException: File document for microflow variable 'downloadpdf' should not be empty when calling download file.     at com.mendix.webui.actions.microflow.DownloadFileAction.addDownloadFileFeedback(DownloadFileAction.scala:30)     at com.mendix.webui.actions.microflow.DownloadFileAction.$anonfun$execute$1(DownloadFileAction.scala:19)     at com.mendix.webui.actions.microflow.DownloadFileAction.$anonfun$execute$1$adapted(DownloadFileAction.scala:19)     at scala.Option.foreach(Option.scala:437)     at com.mendix.webui.actions.microflow.DownloadFileAction.execute(DownloadFileAction.scala:19)     at com.mendix.webui.actions.microflow.DownloadFileAction.execute(DownloadFileAction.scala:10)     at com.mendix.modules.microflowengine.microflow.impl.MicroflowObject.$anonfun$execute$1(MicroflowObject.scala:31)     at scala.Option.flatMap(Option.scala:283)     at com.mendix.modules.microflowengine.microflow.impl.MicroflowObject.execute(MicroflowObject.scala:28)     at com.mendix.modules.microflowengine.microflow.impl.MicroflowImpl.$anonfun$executeAfterBreakingIfNecessary$2(MicroflowImpl.scala:167)     at scala.Option.flatMap(Option.scala:283)     at com.mendix.modules.microflowengine.microflow.impl.MicroflowImpl.executeAfterBreakingIfNecessary(MicroflowImpl.scala:167)     at com.mendix.modules.microflowengine.microflow.impl.MicroflowImpl.executeAction(MicroflowImpl.scala:114)     at com.mendix.systemwideinterfaces.core.UserAction.execute(UserAction.java:46)     at com.mendix.basis.actionmanagement.CoreActionHandlerImpl.doCall(CoreActionHandlerImpl.scala:63)     at com.mendix.basis.actionmanagement.CoreActionHandlerImpl.call(CoreActionHandlerImpl.scala:48)     at com.mendix.core.actionmanagement.CoreAction.call(CoreAction.java:54)     at com.mendix.basis.actionmanagement.ActionManagerBase.lambda$executeSync$0(ActionManagerBase.java:151)     at com.mendix.util.classloading.Runner.withContextClassLoader(Runner.java:19)     at com.mendix.basis.actionmanagement.ActionManagerBase.executeSync(ActionManagerBase.java:149)     at com.mendix.basis.actionmanagement.MicroflowCallBuilderImpl.execute(MicroflowCallBuilderImpl.scala:41)     at com.mendix.webui.actions.client.ExecuteMicroflowAction.runMicroflow(ExecuteMicroflowAction.scala:76)     at com.mendix.webui.actions.client.ExecuteMicroflowAction.$anonfun$apply$3(ExecuteMicroflowAction.scala:42)     at com.mendix.webui.actions.client.RegularClientAction$Helpers$.$anonfun$liftEither$1(RegularClientAction.scala:29)     at com.mendix.webui.actions.client.RegularClientAction$Helpers$StateHandler.$anonfun$apply$4(RegularClientAction.scala:55)     at com.mendix.webui.requesthandling.helpers.StateHandling.withState(StateHandling.scala:37)     at com.mendix.webui.requesthandling.helpers.StateHandling.withState$(StateHandling.scala:34)     at com.mendix.webui.actions.client.RegularClientAction$Helpers$StateHandler.withState(RegularClientAction.scala:45)     at com.mendix.webui.actions.client.RegularClientAction$Helpers$StateHandler.apply(RegularClientAction.scala:53)     at com.mendix.webui.actions.client.RegularClientAction$Helpers$StateHandler.apply(RegularClientAction.scala:45)     at com.mendix.webui.actions.client.ExecuteMicroflowAction.apply(ExecuteMicroflowAction.scala:43)     at com.mendix.webui.actions.client.ExecuteMicroflowAction.apply(ExecuteMicroflowAction.scala:22)     at com.mendix.webui.actions.client.RegularClientAction.$anonfun$execute$3(RegularClientAction.scala:109)     at scala.util.Try$.apply(Try.scala:210)     at com.mendix.webui.actions.client.RegularClientAction.$anonfun$execute$2(RegularClientAction.scala:109)     at com.mendix.webui.actions.client.RegularClientAction.$anonfun$execute$2$adapted(RegularClientAction.scala:107)     at com.mendix.webui.requesthandling.helpers.ContextHandling.$anonfun$inContext$5(ContextHandling.scala:45)     at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)     at com.mendix.basis.actionmanagement.ActionMonitoring$.$anonfun$monitor$1(ActionMonitoring.scala:49)     at com.mendix.util.classloading.Runner.withContextClassLoader(Runner.java:19)     at com.mendix.basis.actionmanagement.ActionMonitoring$.monitor(ActionMonitoring.scala:49)     at com.mendix.webui.requesthandling.helpers.ContextHandling.inContext(ContextHandling.scala:45)     at com.mendix.webui.requesthandling.helpers.ContextHandling.inContext$(ContextHandling.scala:26)     at com.mendix.webui.actions.client.RegularClientAction.inContext(RegularClientAction.scala:86)     at com.mendix.webui.requesthandling.helpers.ContextHandling.inContext(ContextHandling.scala:23)     at com.mendix.webui.requesthandling.helpers.ContextHandling.inContext$(ContextHandling.scala:18)     at com.mendix.webui.actions.client.RegularClientAction.inContext(RegularClientAction.scala:86)     at com.mendix.webui.actions.client.RegularClientAction.$anonfun$execute$1(RegularClientAction.scala:107)     at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)     at com.mendix.webui.requesthandling.helpers.ProfileHandling.profileRequest(ProfileHandling.scala:14)     at com.mendix.webui.requesthandling.helpers.ProfileHandling.profileRequest$(ProfileHandling.scala:10)     at com.mendix.webui.actions.client.RegularClientAction.profileRequest(RegularClientAction.scala:86)     at com.mendix.webui.actions.client.RegularClientAction.execute(RegularClientAction.scala:104)     at com.mendix.webui.requesthandling.ClientRequestHandler.handleAction(ClientRequestHandler.scala:106)     at com.mendix.webui.requesthandling.ClientRequestHandler.processRequest(ClientRequestHandler.scala:79)     at com.mendix.externalinterface.connector.RequestHandler.doProcessRequest(RequestHandler.java:35)     at com.mendix.external.connector.MxRuntimeConnector.lambda$processRequest$0(MxRuntimeConnector.java:74)     at com.mendix.util.classloading.Runner.withContextClassLoader(Runner.java:19)     at com.mendix.external.connector.MxRuntimeConnector.processRequest(MxRuntimeConnector.java:73)     at com.mendix.basis.impl.MxRuntimeImplBase.processRequest(MxRuntimeImplBase.java:834)     at com.mendix.m2ee.appcontainer.server.handler.RuntimeServlet.service(RuntimeServlet.java:42)     at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)     at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:791)     at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1626)     at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:228)     at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)     at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)     at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:548)     at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)     at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624)     at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)     at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1435)     at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)     at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501)     at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594)     at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)     at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1350)     at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)     at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)     at org.eclipse.jetty.server.Server.handle(Server.java:516)     at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:388)     at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:633)     at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:380)     at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:279)     at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)     at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105)     at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104)     at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336)     at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313)     at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171)     at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:129)     at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:383)     at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:882)     at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1036)     at java.base/java.lang.Thread.run(Thread.java:834)   other error:  Error     at h (http://localhost:8080/mxclientsystem/mxui/mxui.js?637714028362318199:73:31048)     at async http://localhost:8080/mxclientsystem/mxui/mxui.js?637714028362318199:73:23222     at async o (http://localhost:8080/mxclientsystem/mxui/mxui.js?637714028362318199:73:29410)     at async c (http://localhost:8080/mxclientsystem/mxui/mxui.js?637714028362318199:73:30544)     at async h.executeMicroflow (http://localhost:8080/mxclientsystem/mxui/mxui.js?637714028362318199:73:18083)     at async http://localhost:8080/mxclientsystem/mxui/mxui.js?637714028362318199:73:6577   Generate doc :-
asked
3 answers
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NullPointerException means that there is something being used in an expression or in your document that does not have a value.  Your screenshots don’t show the whole stacktrace so I can’t see the specifics of the error.

For instance, if you created a decimal variable and added to numbers to determine the value of it, you would get this error if one of the numbers was empty.

If you can post the whole stacktrace, I can be more specific about the reason for this error.

answered
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Did you pass the required parameters? From your error it seems that one of them is empty.
Check this https://docs.mendix.com/refguide/generate-document for more details.

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Hi 

Can you share the screenshot of your generat document action. I suspect there is some null object is being passed to the parameter or missing required parameter.

answered