Showcase-portlet:
There are new warnings and errors written to the server log when adding any component portlet to the page, or when refreshing the page to render the component:

22:26:25,282 WARN [ExternalContextCompat_2_0_Impl:96] Unable to call portletResponse.addProperty(String, String) for portletResponse=[com.liferay.faces.bridge.filter.internal.RenderResponseBridgeLiferayImpl] because it is not a ResourceRes
ponse.
22:26:25,283 WARN [ExternalContextCompat_2_0_Impl:96] Unable to call portletResponse.addProperty(String, String) for portletResponse=[com.liferay.faces.bridge.filter.internal.RenderResponseBridgeLiferayImpl] because it is not a ResourceRes
ponse.
22:26:25,315 WARN [HeadResponseWriterBase:177] Title removed because multiple <title> elements are invalid and the
portlet container controls the <title>.
22:26:28,213 ERROR [http-bio-8080-exec-15][PollerServlet:63] No channel exists with user id 10199
22:26:28,331 ERROR [http-bio-8080-exec-15][status_jsp:752] No channel exists with user id 10199