I tried to upgrade from 5.6.1. to 5.6.2 but it crashed. I had backed up both the site and the database. I restored them both but now have an error when I log in as admin or host. The site appears to be working though. 

It says that the "Object reference not set to an instance of an object". The complete message is below. Has it lost a reference to a folder? I am not sure where to start to try and sort out the error message. Any pointer will be appreciated.

DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at DotNetNuke.Services.FileSystem.FolderController.GetFolder(Int32 PortalID, String FolderPath, Boolean ignoreCache) at DotNetNuke.Common.Utilities.FileSystemUtils.GetFolder(Int32 PortalID, String FolderPath) at DotNetNuke.Common.Globals.GetFileList(Int32 PortalId, String strExtensions, Boolean NoneSpecified, String Folder, Boolean includeHidden) at DotNetNuke.UI.ControlPanel.AddPage.LoadTemplateList() at DotNetNuke.UI.ControlPanel.AddPage.LoadAllLists() at DotNetNuke.UI.ControlPanel.AddPage.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

Thanks for that Sebastian, I have looked through and haven't found anything in particular. I notice also though that under the Admin menu Site Settings, User Accounts and File Manager all come up with error messages. 

I am worried that this is not looking good. 

net 4.0 (integrated pipeline)

thanks Costas.