In older IE browsers, when the dataExporter button is clicked a new window is opened which facilitates the download of the file. Upon clicking the "Close Window" button an NPE is thrown in the server logs:

java.lang.NullPointerException
at java.io.ByteArrayInputStream.<init>(ByteArrayInputStream.java:89)
at org.icefaces.ace.component.dataexporter.ExporterResource.getInputStream(ExporterResource.java:47)
at org.icefaces.application.ResourceRegistry.handleResourceRequest(ResourceRegistry.java:152)
at org.icefaces.impl.application.WindowScopeManager.handleSessionAwareResourceRequest(WindowScopeManager.java:69)
at org.icefaces.impl.application.SessionAwareResourceHandlerWrapper.handleResourceRequest(SessionAwareResourceHandlerWrapper.java:40)
at javax.faces.application.ResourceHandlerWrapper.handleResourceRequest(ResourceHandlerWrapper.java:125)
at org.icefaces.impl.application.SessionTimeoutMonitor.handleSessionAwareResourceRequest(SessionTimeoutMonitor.java:71)
at org.icefaces.impl.application.SessionAwareResourceHandlerWrapper.handleResourceRequest(SessionAwareResourceHandlerWrapper.java:40)

This doesn't seem to have a function impact. Also if using the windows close button instead of the link, this issue isn't seen.