Consider the following scenario:
You enable publishing on a Microsoft SharePoint Server 2010 server.
You create a new sub site in the root of a site collection.
The sub site is displayed in the Home Page navigation bar.
You delete the sub site.
In this scenario, the sub site is still displayed in the Home Page navigation bar. Then, when you update the Home Page, the word Error is displayed in the navigation bar.
To resolve this issue, apply the following update:
2817570 Description of the SharePoint Server 2010 cumulative update package (SharePoint server-package): August 13, 2013
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.