Une erreur est survenur lors de la génération du document PDF/ An error has occured during PDF generation

; SystemID: file:/data/cwproducts/progpdf/WEB-INF/xslt/stylesheet.xsl; Line#: 35; Column#: 73
net.sf.saxon.trans.XPathException: org.apache.fop.fo.ValidationException: file:/data/cwproducts/progpdf/WEB-INF/xslt/stylesheet.xsl:35:73: "fo:root" is missing child elements. Required content model: (layout-master-set, declarations?, bookmark-tree?, (page-sequence|fox:external-document)+) (See position 35:73)
	at net.sf.saxon.event.ContentHandlerProxy.handleSAXException(ContentHandlerProxy.java:543)
	at net.sf.saxon.event.ContentHandlerProxy.endElement(ContentHandlerProxy.java:404)
	at net.sf.saxon.event.NamespaceReducer.endElement(NamespaceReducer.java:231)
	at net.sf.saxon.event.ComplexContentOutputter.endElement(ComplexContentOutputter.java:560)
	at net.sf.saxon.expr.instruct.ElementCreator.processLeavingTail(ElementCreator.java:369)
	at net.sf.saxon.expr.instruct.ElementCreator.processLeavingTail(ElementCreator.java:313)
	at net.sf.saxon.expr.instruct.TemplateRule.applyLeavingTail(TemplateRule.java:356)
	at net.sf.saxon.trans.Mode.applyTemplates(Mode.java:456)
	at net.sf.saxon.Controller.transformDocument(Controller.java:2321)
	at net.sf.saxon.Controller.transform(Controller.java:1892)
	at net.sf.saxon.s9api.XsltTransformer.transform(XsltTransformer.java:579)
	at net.sf.saxon.jaxp.TransformerImpl.transform(TransformerImpl.java:185)
	at ProgPDFServlet.getPDF(ProgPDFServlet.java:599)
	at ProgPDFServlet.outputPDF(ProgPDFServlet.java:554)
	at ProgPDFServlet.handleCall(ProgPDFServlet.java:218)
	at ProgPDFServlet.doGet(ProgPDFServlet.java:65)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.ajp.AjpProcessor.service(AjpProcessor.java:394)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:770)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: org.apache.fop.fo.ValidationException: file:/data/cwproducts/progpdf/WEB-INF/xslt/stylesheet.xsl:35:73: "fo:root" is missing child elements. Required content model: (layout-master-set, declarations?, bookmark-tree?, (page-sequence|fox:external-document)+) (See position 35:73)
	at org.apache.fop.events.ValidationExceptionFactory.createException(ValidationExceptionFactory.java:38)
	at org.apache.fop.events.EventExceptionManager.throwException(EventExceptionManager.java:58)
	at org.apache.fop.events.DefaultEventBroadcaster$1.invoke(DefaultEventBroadcaster.java:173)
	at jdk.proxy6/jdk.proxy6.$Proxy29.missingChildElement(Unknown Source)
	at org.apache.fop.fo.FONode.missingChildElementError(FONode.java:588)
	at org.apache.fop.fo.pagination.Root.endOfNode(Root.java:117)
	at org.apache.fop.fo.FOTreeBuilder$MainFOHandler.endElement(FOTreeBuilder.java:360)
	at org.apache.fop.fo.FOTreeBuilder.endElement(FOTreeBuilder.java:190)
	at net.sf.saxon.event.ContentHandlerProxy.endElement(ContentHandlerProxy.java:402)
	... 38 more
---------
org.apache.fop.fo.ValidationException: file:/data/cwproducts/progpdf/WEB-INF/xslt/stylesheet.xsl:35:73: "fo:root" is missing child elements. Required content model: (layout-master-set, declarations?, bookmark-tree?, (page-sequence|fox:external-document)+) (See position 35:73)
	at org.apache.fop.events.ValidationExceptionFactory.createException(ValidationExceptionFactory.java:38)
	at org.apache.fop.events.EventExceptionManager.throwException(EventExceptionManager.java:58)
	at org.apache.fop.events.DefaultEventBroadcaster$1.invoke(DefaultEventBroadcaster.java:173)
	at jdk.proxy6/jdk.proxy6.$Proxy29.missingChildElement(Unknown Source)
	at org.apache.fop.fo.FONode.missingChildElementError(FONode.java:588)
	at org.apache.fop.fo.pagination.Root.endOfNode(Root.java:117)
	at org.apache.fop.fo.FOTreeBuilder$MainFOHandler.endElement(FOTreeBuilder.java:360)
	at org.apache.fop.fo.FOTreeBuilder.endElement(FOTreeBuilder.java:190)
	at net.sf.saxon.event.ContentHandlerProxy.endElement(ContentHandlerProxy.java:402)
	at net.sf.saxon.event.NamespaceReducer.endElement(NamespaceReducer.java:231)
	at net.sf.saxon.event.ComplexContentOutputter.endElement(ComplexContentOutputter.java:560)
	at net.sf.saxon.expr.instruct.ElementCreator.processLeavingTail(ElementCreator.java:369)
	at net.sf.saxon.expr.instruct.ElementCreator.processLeavingTail(ElementCreator.java:313)
	at net.sf.saxon.expr.instruct.TemplateRule.applyLeavingTail(TemplateRule.java:356)
	at net.sf.saxon.trans.Mode.applyTemplates(Mode.java:456)
	at net.sf.saxon.Controller.transformDocument(Controller.java:2321)
	at net.sf.saxon.Controller.transform(Controller.java:1892)
	at net.sf.saxon.s9api.XsltTransformer.transform(XsltTransformer.java:579)
	at net.sf.saxon.jaxp.TransformerImpl.transform(TransformerImpl.java:185)
	at ProgPDFServlet.getPDF(ProgPDFServlet.java:599)
	at ProgPDFServlet.outputPDF(ProgPDFServlet.java:554)
	at ProgPDFServlet.handleCall(ProgPDFServlet.java:218)
	at ProgPDFServlet.doGet(ProgPDFServlet.java:65)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.ajp.AjpProcessor.service(AjpProcessor.java:394)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:770)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1415)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:833)