Hi

I upgraded from DNN6.3.9 to 7.2 and then 7.2.1, now when someone navigates to a non existent page, they get presented with a generic DNN error page (that just says DNNError) and this is logged :

DotNetNuke.Services.Exceptions.PageLoadException: Session state can only be used when enableSessionState is set to true, either in a configuration file or in the Page directive. Please also make sure that System.Web.SessionStateModule or a custom session state module is included in the \\ section in the application configuration. ---> System.Web.HttpException: Session state can only be used when enableSessionState is set to true, either in a configuration file or in the Page directive. Please also make sure that System.Web.SessionStateModule or a custom session state module is included in the \\ section in the application configuration.
at System.Web.UI.Page.get_Session()
at DotNetNuke.Framework.CachePageStatePersister.Save()
at System.Web.UI.Page.SaveAllState()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
--- End of inner exception stack trace ---

I have been through the process of adding the AUM_ErrorPage404 setting in PortalSettings, but that made no difference, this happens whether that setting is there or no. I have also checked (and rechecked) the web.config, it has all the correct settings for the session module.

I have googled the error and just find the same thing over and over, nothing specific to dotnetnuke. Any ideas?