The facelets ui:debug tag is stopping the upload of a file with the inputFile component. This only happens on a slow connection and if the inputFile has implemented the progressListener. Without the ui:debug tag on the page the upload proceeds normally. If the tag is on the page the upload quickly quits and throws the following exception:

org.apache.commons.fileupload.MultipartStream$MalformedStreamException: Stream ended unexpectedly
at org.apache.commons.fileupload.MultipartStream$ItemInputStream.makeAvailable(MultipartStream.java:983)
at org.apache.commons.fileupload.MultipartStream$ItemInputStream.read(MultipartStream.java:887)
at java.io.FilterInputStream.read(Unknown Source)
at org.apache.commons.fileupload.util.LimitedInputStream.read(LimitedInputStream.java:125)
at java.io.FilterInputStream.read(Unknown Source)
at org.apache.commons.fileupload.util.Streams.copy(Streams.java:94)
at org.apache.commons.fileupload.util.Streams.copy(Streams.java:64)
at com.icesoft.faces.webapp.http.core.UploadServer$2.upload(UploadServer.java:197)
at com.icesoft.faces.webapp.http.core.UploadServer$2.servlet(UploadServer.java:115)
at com.icesoft.faces.webapp.http.servlet.ServletRequestResponse.detectEnvironment(ServletRequestResponse.java:262)
at com.icesoft.faces.webapp.http.core.UploadServer.service(UploadServer.java:63)
at com.icesoft.faces.webapp.http.common.standard.PathDispatcherServer.service(PathDispatcherServer.java:24)
at com.icesoft.faces.webapp.http.servlet.BasicAdaptingServlet.service(BasicAdaptingServlet.java:16)
at com.icesoft.faces.webapp.http.servlet.PathDispatcher.service(PathDispatcher.java:23)
at com.icesoft.faces.webapp.http.servlet.SessionDispatcher.service(SessionDispatcher.java:53)
at com.icesoft.faces.webapp.http.servlet.PathDispatcher.service(PathDispatcher.java:23)
at com.icesoft.faces.webapp.http.servlet.MainServlet.service(MainServlet.java:131)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at com.icesoft.faces.webapp.xmlhttp.BlockingServlet.service(BlockingServlet.java:56)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at de.jtel.webapp.common.LoggingFilter.doFilter(LoggingFilter.java:40)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
at java.lang.Thread.run(Unknown Source)