NullPointerException at a UIComponent.encodeAll .. Weblogic/ADF

Please make sure the tag libraries for jsff or jspx pages are valid

e.g

<?xml version='1.0' encoding='UTF-8'?>

<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1" xmlns:af="http://xmlns.oracle.com/adf/faces/rich"

                xmlns:f="http://java.sun.com/jsf/core" xmlns:tr="http://myfaces.apache.org/trinidad">

the one in red could be the reason

   

intermittent issue like below might occur

oracle.adfinternal.view.faces.renderkit.rich.PanelCollectionRenderer$PanelCollectionHelper._renderAutoSizedContent(PanelCollectionRenderer.java:751)

        at oracle.adfinternal.view.faces.renderkit.rich.PanelCollectionRenderer$PanelCollectionHelper._encodeAll(PanelCollectionRenderer.java:949)

        at oracle.adfinternal.view.faces.renderkit.rich.PanelCollectionRenderer$PanelCollectionHelper.access$600(PanelCollectionRenderer.java:634)

        at oracle.adfinternal.view.faces.renderkit.rich.PanelCollectionRenderer.encodeAll(PanelCollectionRenderer.java:495)

        at oracle.adf.view.rich.render.RichRenderer.encodeAll(RichRenderer.java:1600)

        at org.apache.myfaces.trinidad.render.CoreRenderer.encodeEnd(CoreRenderer.java:525)

        at org.apache.myfaces.trinidad.component.UIXComponentBase.encodeEnd(UIXComponentBase.java:1217)

        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1786)

        at org.apache.myfaces.trinidad.render.CoreRenderer.encodeChild(CoreRenderer.java:647)

        at oracle.adfinternal.view.faces.renderkit.rich.PanelStretchLayoutRenderer._encodeCenterPane(PanelStretchLayoutRenderer.java:1308)

        at oracle.adfinternal.view.faces.renderkit.rich.PanelStretchLayoutRenderer._encodeMiddleForFlowing(PanelStretchLayoutRenderer.java:659)

        at oracle.adfinternal.view.faces.renderkit.rich.PanelStretchLayoutRenderer._encodeMiddlePanesFlowing(PanelStretchLayoutRenderer.java:523)

        at oracle.adfinternal.view.faces.renderkit.rich.PanelStretchLayoutRenderer._encodeMiddlePanes(PanelStretchLayoutRenderer.java:359)

        at oracle.adfinternal.view.faces.renderkit.rich.PanelStretchLayoutRenderer.encodeAll(PanelStretchLayoutRenderer.java:315)

        at oracle.adf.view.rich.render.RichRenderer.encodeAll(RichRenderer.java:1600)

        at org.apache.myfaces.trinidad.render.CoreRenderer.encodeEnd(CoreRenderer.java:525)

        at org.apache.myfaces.trinidad.component.UIXComponentBase.encodeEnd(UIXComponentBase.java:1217)

        at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1786)