See below:

com.atlassian.confluence.importexport.ImportExportException: org.apache.velocity.exception.MethodInvocationException: Invocation of method 'exportWikiToXslFo' in class com.atlassian.confluence.importexport.impl.WikiExporter threw exception class com.atlassian.confluence.renderer.WikiRenderException : org.dom4j.DocumentException: Error on line 41 of document : The entity "nbsp" was referenced, but not declared. Nested exception: The entity "nbsp" was referenced, but not declared. at com.atlassian.confluence.importexport.impl.PdfExporter.generateXslFo(PdfExporter.java:204) at com.atlassian.confluence.importexport.impl.PdfExporter.doExportEntity(PdfExporter.java:136) at com.atlassian.confluence.importexport.impl.AbstractRendererExporterImpl.exportSpace(AbstractRendererExporterImpl.java:110) at com.atlassian.confluence.importexport.impl.AbstractRendererExporterImpl.doExport(AbstractRendererExporterImpl.java:92) at com.atlassian.confluence.importexport.impl.PdfExporter.doExport(PdfExporter.java:80) at com.atlassian.confluence.importexport.DefaultImportExportManager.exportAs(DefaultImportExportManager.java:84) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:324) at org.springframework.aop.framework.AopProxyUtils.invokeJoinpointUsingReflection(AopProxyUtils.java:59) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:201) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:176) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:154) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:196) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:135) at $Proxy18.exportAs(Unknown Source) at com.atlassian.confluence.importexport.actions.ExportSpaceAction.execute(ExportSpaceAction.java:132) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:171) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.interceptor.DefaultWorkflowInterceptor.intercept(DefaultWorkflowInterceptor.java:58) at com.atlassian.confluence.core.ConfluenceWorkflowInterceptor.intercept(ConfluenceWorkflowInterceptor.java:32) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37) at com.atlassian.confluence.core.ConfluenceValidationInterceptor.intercept(ConfluenceValidationInterceptor.java:18) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.atlassian.confluence.security.actions.PermissionCheckInterceptor.intercept(PermissionCheckInterceptor.java:40) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:37) at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168) at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:116) at com.opensymphony.webwork.dispatcher.ServletDispatcher.serviceAction(ServletDispatcher.java:182) at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:162) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:129) at com.atlassian.confluence.util.profiling.ProfilingPageFilter.parsePage(ProfilingPageFilter.java:36) at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:61) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:161) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:181) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:96) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:100) at com.atlassian.confluence.setup.SpringSessionInViewFilter.doFilterInternal(SpringSessionInViewFilter.java:32) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:57) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:38) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:193) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:781) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:549) at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:589) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:666) at java.lang.Thread.run(Thread.java:534) Caused by: org.apache.velocity.exception.MethodInvocationException: Invocation of method 'exportWikiToXslFo' in class com.atlassian.confluence.importexport.impl.WikiExporter threw exception class com.atlassian.confluence.renderer.WikiRenderException : org.dom4j.DocumentException: Error on line 41 of document : The entity "nbsp" was referenced, but not declared. Nested exception: The entity "nbsp" was referenced, but not declared. at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:309) at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:207) at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:250) at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:94) at org.apache.velocity.runtime.directive.Foreach.render(Foreach.java:344) at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:153) at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:271) at org.apache.velocity.Template.merge(Template.java:296) at com.atlassian.confluence.util.TemplateSupport.processTemplate(TemplateSupport.java:79) at com.atlassian.confluence.importexport.impl.PdfExporter.generateXslFo(PdfExporter.java:200) ... 98 more