When using an f:param with the ace:linkButton that doesn't use a String object the following exception is thrown:

java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String
at org.icefaces.ace.util.Utils.asParameterString(Utils.java:288)
at org.icefaces.ace.component.linkbutton.LinkButtonRenderer.encodeHref(LinkButtonRenderer.java:122)
at org.icefaces.ace.component.linkbutton.LinkButtonRenderer.encodeBegin(LinkButtonRenderer.java:102)
at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:822)
at org.icefaces.ace.renderkit.CoreRenderer.renderChild(CoreRenderer.java:75)
at org.icefaces.ace.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:66)
at org.icefaces.ace.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:238)
at org.icefaces.ace.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:135)
at org.icefaces.ace.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:73)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:877)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1826)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at org.icefaces.impl.renderkit.RendererWrapper.encodeChildren(RendererWrapper.java:49)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:847)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1819)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1822)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1822)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:447)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:125)
at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:286)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:722)

This is only an issue with the ICEfaces 3.3.0 and recent releases. Testing with the EE 3.2.0 release does not cause this error. This is likely due to the changes made in ICE-8944.