Exception: A connector should not be marked as dirty while a response is be

I have a combobox for currency. it has eu and dollar value in it
if I select/click the combobox and press down arrow everything will be showed, then i can type eu or press down and choose eu. both way work ok
but if i click on combobox and type e for eu immediately (without open the dropdown or press the arrow down) then i get this error.
what does this error mean and are there anyway to avoid it?

java.lang.IllegalStateException: A connector should not be marked as dirty while a response is being written.
    at com.vaadin.ui.ConnectorTracker.markDirty(ConnectorTracker.java:414) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.AbstractClientConnector.markAsDirty(AbstractClientConnector.java:141) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.ui.AbstractSelect.fireItemSetChange(AbstractSelect.java:1730) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.ui.AbstractSelect.containerItemSetChange(AbstractSelect.java:1697) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.ui.ComboBox.containerItemSetChange(ComboBox.java:465) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.data.util.AbstractContainer.fireItemSetChange(AbstractContainer.java:242) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.data.util.AbstractContainer.fireItemSetChange(AbstractContainer.java:228) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.data.util.AbstractInMemoryContainer.filterAll(AbstractInMemoryContainer.java:488) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.data.util.AbstractInMemoryContainer.addFilter(AbstractInMemoryContainer.java:583) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.data.util.AbstractBeanContainer.addContainerFilter(AbstractBeanContainer.java:385) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.ui.ComboBox.getOptionsWithFilter(ComboBox.java:385) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.ui.ComboBox.paintContent(ComboBox.java:226) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.LegacyPaint.paint(LegacyPaint.java:65) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.communication.LegacyUidlWriter.write(LegacyUidlWriter.java:82) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.communication.UidlWriter.write(UidlWriter.java:139) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.communication.UidlRequestHandler.writeUidl(UidlRequestHandler.java:155) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:101) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:41) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1408) ~[vaadin-server-7.5.5.jar:7.5.5]
    at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:351) [vaadin-server-7.5.5.jar:7.5.5]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-embed-websocket-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) [spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_79]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_79]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at java.lang.Thread.run(Thread.java:745) [na:1.7.0_79]