How do I avoid "Exception handling request to" javax.servlet.ServletException when redirecting? - jsf

Question

I have logic in my backing bean that redirects if there is a session timeout.
FacesContext.getCurrentInstance().getExternalContext().setResponseStatus(responseCode);
FacesContext.getCurrentInstance().getExternalContext().setResponseHeader("Location", redirectURL);
FacesContext.getCurrentInstance().responseComplete();
However, the page that is being loaded still attempts to render, and throws this error:
2021-11-27 08:02:50,774 ERROR [io.undertow.request] (default task-2) UT005023: Exception handling request to /dashboard/mypage.htm: javax.servlet.ServletException
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:236)
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
at org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:294)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at org.apache.myfaces.webapp.filter.ExtensionsFilter.doFilter(ExtensionsFilter.java:357)
at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
Caused by: java.lang.NullPointerException
at javax.el.ELUtil.buildParameters(ELUtil.java:699)
at javax.el.ELUtil.invokeMethod(ELUtil.java:243)
at javax.el.BeanELResolver.invoke(BeanELResolver.java:338)
at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:198)
at com.sun.el.parser.AstValue.getValue(AstValue.java:111)
at com.sun.el.parser.AstValue.getValue(AstValue.java:179)
at com.sun.el.parser.AstDeferredExpression.getValue(AstDeferredExpression.java:39)
at com.sun.el.parser.AstCompositeExpression.getValue(AstCompositeExpression.java:44)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:202)
at org.apache.myfaces.view.facelets.el.ContextAwareTagValueExpression.getValue(ContextAwareTagValueExpression.java:93)
at javax.faces.component._DeltaStateHelper.eval(_DeltaStateHelper.java:372)
at org.primefaces.component.menuitem.UIMenuItemBase.getUrl(UIMenuItemBase.java:91)
at org.primefaces.renderkit.MenuItemAwareRenderer.encodeOnClick(MenuItemAwareRenderer.java:67)
at org.primefaces.component.menu.BaseMenuRenderer.encodeMenuItem(BaseMenuRenderer.java:111)
at org.primefaces.component.menu.BaseMenuRenderer.encodeMenuItem(BaseMenuRenderer.java:69)
at org.primefaces.component.tieredmenu.TieredMenuRenderer.encodeElements(TieredMenuRenderer.java:124)
at org.primefaces.component.menubutton.MenuButtonRenderer.encodeMenu(MenuButtonRenderer.java:147)
at org.primefaces.component.menubutton.MenuButtonRenderer.encodeMarkup(MenuButtonRenderer.java:68)
at org.primefaces.component.menu.BaseMenuRenderer.encodeEnd(BaseMenuRenderer.java:50)
How can I get the view to stop loading on this workflow? It's obvious that, since the redirect occurred, the backing bean hasn't loaded everything and therefore EL expressions that depend on such objects being loaded, are failing.
I don't want to generate the error because this causes my admins grief because of the error emails that get generated. They can't tell if it is a real error or not.

Answer 1

Looks like you should have put some value on attribute in the request and that page uses that attribute and displays the nullPointer Exception as an error try to HttpServletRequest.setAttribute("bla", bla) nad check it.