When migrating from SharePoint 2007 to SharePoint 2010, it might be possible that your navigation is broken. The error I encountered was the following, but it can occur in more functions within the Navigation namespace.
Object Reference not set to an instance of an object. Stacktrace: at Microsoft.SharePoint.Publishing.Navigation.PortalSiteWebSiteMapNode.FetchDynamicItems(PublishingWeb pubWeb, NodeTypes includedTypes, Boolean& websFetched, Boolean& pagesFetched) at Microsoft.SharePoint.Publishing.Navigation.PortalWebSiteMapNode.PopulateNavigationChildrenInner(NodeTypes includedTypes)
This error can arise when you restored a SharePoint site to SharePoint 2010, and that site was created in a language which had it's default "Pages Library" location changed.
- English pages library was located at "Pages" and not changed
- The German pages library was called "Seiten" (if i recall it correctly), and is not changed
- The dutch pages library was called "Pages" (and thus, not localized), but has the default location of "Paginas" in SharePoint 2010 (so it's location was changed)
When a SP2007 site is migrated to SP2010, the navigation provider expects that any changes to the default location, is stored in a specific property, which, apparently, isn't the case, after a migration.
Luckily, Microsoft provided a powershell for this to fix it. And no, it has not been fixed in SP1. Check the following link for the exact cause and resolution: